Wheel spacers

[albertb]

I just put on a 6 inch lift and I want to widen my stance for stability and keep the stock wheels. I ordered a set of 1.5" 70.5mm bore wheel spacers. They won't clear the front manual hubs (true D35) and the bore was too big for the rear (8.8 axle). Has anyone found a wheel spacer setup that works? Thanks

 

[JoshT]

I'm not an anti-spacer person. I have them on my truck with stock wheels and stock size tires. It's rarely on anything rougher than a dirt driveway, and will be getting proper wheels and smaller tires as soon as I can get the suspension finalized. In a situation like yours I'd really recommend rethinking the spacer and wheel situation.

Adding a 6" lift generally means that you're planning to run much larger tires. That by itself is a lot of added weight and stress. Adding spacers is going to multiply that stress. Then being used in offroad situations is also going to have an effect on the loads and stresses transfered to the bearings.

If you're going to do it, make sure you are keeping an eye on the condition of your wheel bearings. Also make sure you torque the spacers and check them regularly. I mean actually pull the wheel off and check/retorque the spacer, lugnuts working loose is probably the #1 spacer related failure, with bearings likely being the second.

Now that I've said my 2 cent about spacers, on to your issue.

The center bore of your wheels should be 70.5mm. The spacers that you have claim to be 70.5mm, so if they don't fit I'd be finding a set of calipers and measuring their bore. My guess is that their listed measurement is off and they are a little undersized. My first move would be to verify that the spacer actually specification and consult the manufacturer of it does not. Barring a solution there, I'd return them and find a better brand that run true to size or go slightly oversized on the bore. As a last resort (unless I had a lather), I would probably machine off the small amount from the bore on your current spacers to clear the hub.

I wouldn't worry too much about them being a loose fit to the hub and axle register (raised part on back axle), you'll just be running them as lug centric instead of hub centric. With the acorn style lug nuts, running lug centric, or centered by the lugs, is no problem. There are a whole lot of Rangers and other vehicles running around out there with lug centric wheels and never had a problem because of it.

 

[MaicoDoug]

I'm such a PITA......

Albert, please post a pic of your baby when she's done.

 

[lil_Blue_Ford]

I'm not an anti-spacer person. I have them on my truck with stock wheels and stock size tires. It's rarely on anything rougher than a dirt driveway, and will be getting proper wheels and smaller tires as soon as I can get the suspension finalized. In a situation like yours I'd really recommend rethinking the spacer and wheel situation.

Adding a 6" lift generally means that you're planning to run much larger tires. That by itself is a lot of added weight and stress. Adding spacers is going to multiply that stress. Then being used in offroad situations is also going to have an effect on the loads and stresses transfered to the bearings.

If you're going to do it, make sure you are keeping an eye on the condition of your wheel bearings. Also make sure you torque the spacers and check them regularly. I mean actually pull the wheel off and check/retorque the spacer, lugnuts working loose is probably the #1 spacer related failure, with bearings likely being the second.

Now that I've said my 2 cent about spacers, on to your issue.

The center bore of your wheels should be 70.5mm. The spacers that you have claim to be 70.5mm, so if they don't fit I'd be finding a set of calipers and measuring their bore. My guess is that their listed measurement is off and they are a little undersized. My first move would be to verify that the spacer actually specification and consult the manufacturer of it does not. Barring a solution there, I'd return them and find a better brand that run true to size or go slightly oversized on the bore. As a last resort (unless I had a lather), I would probably machine off the small amount from the bore on your current spacers to clear the hub.

I wouldn't worry too much about them being a loose fit to the hub and axle register (raised part on back axle), you'll just be running them as lug centric instead of hub centric. With the acorn style lug nuts, running lug centric, or centered by the lugs, is no problem. There are a whole lot of Rangers and other vehicles running around out there with lug centric wheels and never had a problem because of it.

I was going to post up my own thread but since you’ve already answered some of the questions I was going to ask here, well… lol

Any chance you have a particular brand to recommend? I was looking on Amazon (they are all either made in China or don’t say where) and I got rather concerned by multiple people saying they had lugs strip out, the spacers cracking when the lugs were tightened, or the thing flying off going down the road. I realize there could be some user error, but it’s still concerning. Then when you think about it, most of them for a 1.5” thick spacer are only a shade over $20 each and include a set of lug nuts for mounting it. That seems a tad cheap for something quality. The EBay ones are cheaper, but nothing with reviews.

Summit Racing has a set, doesn’t say where they are made, but solid reviews. And they are $154 a pair. At $77 each, that should pay for some quality. Maybe. My pockets currently aren’t that deep.

As a side note to the original poster, I’m trying to fit 18x8” Explorer rims on my Ranger which to achieve the same position on the truck as the 15x7” Ranger rims requires a 1.5” spacer. The Explorer rims I’m using have a much deeper back set, so despite a spacer, I’m really just regaining stock position, which shouldn’t substantially affect wheel bearing life.

 

[lil_Blue_Ford]

I just put on a 6 inch lift and I want to widen my stance for stability and keep the stock wheels. I ordered a set of 1.5" 70.5mm bore wheel spacers. They won't clear the front manual hubs (true D35) and the bore was too big for the rear (8.8 axle). Has anyone found a wheel spacer setup that works? Thanks

I’m going to point out from my own experience…

Most Ranger rims seem to be 7” wide. If you’re going to run a 33x12.50 or 35x12.50, or any wider tire like that, they really should be mounted on a rim that is 8-10” wide. You can put them on a 7” rim, but I’ve found it to cause a problem that relates to correct tire pressure and tire wear. It’s also a bit of a problem with an 8” wide rim, but a little more tolerable. I discovered this all with the process of building my Choptop Bronco II. Currently I’m running 35x12.50-15 tires on 15x8” wagon wheels that I bought aftermarket, think I went with a 4.5” backspace. I can double check that. I wish I would have gone a little less on the backspace, maybe 4”, since I get a little rub on the extended arms at full lock. It’s stanced out wide enough as it sits though, the tires stick about 2” out of the top of the wheel arches and it rides pretty stable.

Now, it has 5” of suspension lift and a 2” body lift. So kind of similar to what a 6” suspension lift will get you. I’m probably lighter than a Ranger, but I do have the 4.0 in mine since I did the swap so we are equal motor-wise. I have to run the tires at about 10-12 psi on the street to wear 80-90% across the tread. 32-35 psi would rattle your teeth out with the ride and I was only making about a dime sized contact patch with the road. If you want to check how you’re wearing, draw a chalk line across your tread and drive across a parking lot. You will see where the chalk wears off and where it doesn’t. Adjust your tire pressure until you’re wiping most of the line off the tread. I should do a video on this one of these days.

Anyway, so now that I’ve explained all of that, guess where one of those tires needs to be in terms of tire pressure on a 7” wide rim? 5-7 psi. I’m not sure I’m comfortable driving on the street with those numbers. Maybe. I know I wasn’t happy with that number and I was originally not super excited about the 10-12 psi either, but I liked it a lot more than 5-7 psi. I really didn’t want to go to a 10” wide rim on a truck that does get driven off-road and a lot of aftermarket sizing at the time ran either 8” or 10” wide. Your results may vary. But I’d probably consider aftermarket rims and change the backspace to get where you want over spacers.

The reason I’m going spacers on my green Ranger to use a stock Explorer rim is because I’m trying for a bit of a sleeper vibe. It’s lowered, 5.0 v8, AWD. The exhaust is a little louder than it should really be for a sleeper, but with aftermarket rims it would really start to stick out. 18” Explorer rims and smaller sidewall tires give me a little performance boost in cornering but make the truck appear like I straight piped it and put Explorer rims on, not turned it into a beast.

Oh, and here is the Choptop…

 

[rubydist]

I bought these nearly 4 years ago and they are great: https://www.ebay.com/itm/264865316090

I don't know if they fit your truck, but I wanted ones that have the hub centric pilot and these do.

When you put the spacers on, use at least blue loctite or maybe even red to make sure the spacers do not come loose.

 

[JoshT]

Warning, long reply inbound...

Any chance you have a particular brand to recommend? I was looking on Amazon (they are all either made in China or don’t say where) and I got rather concerned by multiple people saying they had lugs strip out, the spacers cracking when the lugs were tightened, or the thing flying off going down the road. I realize there could be some user error, but it’s still concerning. Then when you think about it, most of them for a 1.5” thick spacer are only a shade over $20 each and include a set of lug nuts for mounting it. That seems a tad cheap for something quality. The EBay ones are cheaper, but nothing with reviews.

I do not. The ones I've purchased and used came from Amazon and most likely made in China. I read similar reviews, attributed most of them to installer and user error. That said, there are some on there where the reviews make it glaringly obvious that it is just a bad product.

I've run two "sets" of Amazon spacers between three different vehicles. I can't say that I haven't had a problem, but I can say that problem was not caused by the spacer. The first set was 2" spacers that I ran for a bit on the rear axle of my F-100, that generation had a narrow rear track width. The next "set" was the 1" front and 1.5" rear that I've used on two Rangers, set in quotes because it's actually two sets used together.

The F-100 is the one where I had a problem, but it was not caused by the spacer. It was installer error and neglect, AKA my fault. You see that old truck had a hard life before I got it. The drums on the rear axle actually had some oblonging of the stud holes, but it was slight and had never been an issue with the steel wheels. In addition to being oblonged, they had a slight protruding edge around one side of the hole. I ignored that when I shouldn't have. I recall even making mental note of it when I installed the spacers and wheels, but didn't do anything about it because it had always been there and never been an issue. Well aluminum is softer than steel. Where the steel wheel had clamped and held tight, the softer aluminum material seated further over several miles and allowed the lug nuts to loosen. This guy right here never pulled the wheel off and rechecked the spacers. Few hundred miles later I started hearing a rattle while driving down the road, couldn't locate it. Eventually decided it was one of those things I'd find it and fix it when it breaks. It's an old truck, it sat in dad's yard for over a decade, it's got rattles and bound to develop a few new ones right. Well I definitely found what needed to be fixed when the wheel, spacer attached, left the chat. Lugs holding the wheel to the spacer were tight, no damage what so ever to the wheel. Looking at drum face and spacer, you could see where the raised edges had worked into the aluminum and allowed the it to start shifting. If I'd even once pulled the wheel and checked the spacer lugs, I likely wouldn;t have had a problem. I fully believe that if I had installed an aluminum wheel, instead of steel wheel and spacer, I'd have had the exact same problem. Primary difference being that I probably would have cought it before it actually failed.

The ones on the Ranger have a fair bit more miles on them. I can't say how many miles dad put on the spacers I'm currently running while we had the Explorer wheels on his truck, but no problem then. I've had them on my Ranger with the stock wheels for a few tanks of gas, so a few hundred miles, with no issue. At some point after installing on both Rangers the wheels were pulled back off and the spacers were still tight.

I'll also admit that torque may have been a contributing factor in the different experiences between the trucks. I actually put a torque wrench on the Ranger spacers may be a contributing factor. I probably just used the 4-way lug wrench on the F-100, but I can actually apply more torque with it than the torque wrench and just using the 4 way has never been an issue with wheel installs in the past. Having even torque can be just as important as being tight enough, and having that torque wrench clicks means that it has definitely reach torque rather than just hoping that it has. I'm still convinced that the largest contributing factor to the failure on the F-100 was the wear on the drum face around the stud holes, raised edges around the holes prevented the spacer from seating properly, then the softer aluminum allowed it to conform and loosen up the lug nuts.

Summit Racing has a set, doesn’t say where they are made, but solid reviews. And they are $154 a pair. At $77 each, that should pay for some quality. Maybe. My pockets currently aren’t that deep.

Could be better, could be the exact same thing in a different box. Before buying I went in search of a better option than the eBay specials. Searched up what people reviewed as being good outside of amazon/ebay. Honestly, the majority of what I found looked like the same spacer with a different label on the box, and the webpages didn't install any better opinion of the product/seller than the Amazon/eBay listings did. The few that did appear better put the price well beyond what I could stomach to pay. Spacers were never intended to be a perminent solution where I used them.

On the F-100 the spacers were installed to determine if I wanted to acquire and install a wider rear axle. I most definitely do and it was worth the $40 to make that determination.

For the Ranger it was intended to help decide on fitment and to make the 18" Explorer wheels usable until I could get spend on aftermarket wheels. Again, worth the expense. I just didn't both to remove them when I switched from the Explorers back to the stock wheels. Once we get a solution to the control arm problem it'll be going back down and the Explorer wheels will go back on until I get the aftermarkets.

As a side note to the original poster, I’m trying to fit 18x8” Explorer rims on my Ranger which to achieve the same position on the truck as the 15x7” Ranger rims requires a 1.5” spacer. The Explorer rims I’m using have a much deeper back set, so despite a spacer, I’m really just regaining stock position, which shouldn’t substantially affect wheel bearing life.

Are you trying to achieve the same outside edge position or the same center line position? If you want the face of the wheel to sit in the same spot, you probably want a 1" spacer. If you want the center line in the same spot, the 1.5" might be about right.

This link can help visualize offsets and spacer sizes. https://jr-wheels.com/et-calculator

stock vs Ex 18x8 w/ 1" spacer

stock vs Ex 18x8 w/ ~1.5" spacer

Actually a 32mm spacer would have the center lines of the wheels match, that converts to about 1.25 inch.

A 20mm spacer would make the faces match, that converts to about to 3/4 inch, but may be too thin for a bolt on spacer. They do sell them, but would probably require trimming the wheel studs.

 

[lil_Blue_Ford]

Warning, long reply inbound...

Fair enough, I have a big cup of coffee handy…

I do not. The ones I've purchased and used came from Amazon and most likely made in China. I read similar reviews, attributed most of them to installer and user error. That said, there are some on there where the reviews make it glaringly obvious that it is just a bad product.

I was willing to accept that there’s going to be a certain amount of error. I’m just a little concerned knowing how hard I’m willing to drive the truck when there are multiple reviews complaining about major failures and yeah, most of them look identical so what do you do? Add in that most things from China are pretty poor quality especially when it comes to metal.

I've run two "sets" of Amazon spacers between three different vehicles. I can't say that I haven't had a problem, but I can say that problem was not caused by the spacer. The first set was 2" spacers that I ran for a bit on the rear axle of my F-100, that generation had a narrow rear track width. The next "set" was the 1" front and 1.5" rear that I've used on two Rangers, set in quotes because it's actually two sets used together.

The F-100 is the one where I had a problem, but it was not caused by the spacer. It was installer error and neglect, AKA my fault. You see that old truck had a hard life before I got it. The drums on the rear axle actually had some oblonging of the stud holes, but it was slight and had never been an issue with the steel wheels. In addition to being oblonged, they had a slight protruding edge around one side of the hole. I ignored that when I shouldn't have. I recall even making mental note of it when I installed the spacers and wheels, but didn't do anything about it because it had always been there and never been an issue. Well aluminum is softer than steel. Where the steel wheel had clamped and held tight, the softer aluminum material seated further over several miles and allowed the lug nuts to loosen. This guy right here never pulled the wheel off and rechecked the spacers. Few hundred miles later I started hearing a rattle while driving down the road, couldn't locate it. Eventually decided it was one of those things I'd find it and fix it when it breaks. It's an old truck, it sat in dad's yard for over a decade, it's got rattles and bound to develop a few new ones right. Well I definitely found what needed to be fixed when the wheel, spacer attached, left the chat. Lugs holding the wheel to the spacer were tight, no damage what so ever to the wheel. Looking at drum face and spacer, you could see where the raised edges had worked into the aluminum and allowed the it to start shifting. If I'd even once pulled the wheel and checked the spacer lugs, I likely wouldn;t have had a problem. I fully believe that if I had installed an aluminum wheel, instead of steel wheel and spacer, I'd have had the exact same problem. Primary difference being that I probably would have cought it before it actually failed.

The ones on the Ranger have a fair bit more miles on them. I can't say how many miles dad put on the spacers I'm currently running while we had the Explorer wheels on his truck, but no problem then. I've had them on my Ranger with the stock wheels for a few tanks of gas, so a few hundred miles, with no issue. At some point after installing on both Rangers the wheels were pulled back off and the spacers were still tight.

That is a little more reassuring to hear. Ideally once I get the tires I want on the rims, the only time the spacers should come off is to do brakes or service the axle. I was kind of hoping to fit the rims on and wear out the tires that came with them, but I’ll have to either replace those tires before the snow flies or put my 31’s back on.

I'll also admit that torque may have been a contributing factor in the different experiences between the trucks. I actually put a torque wrench on the Ranger spacers may be a contributing factor. I probably just used the 4-way lug wrench on the F-100, but I can actually apply more torque with it than the torque wrench and just using the 4 way has never been an issue with wheel installs in the past. Having even torque can be just as important as being tight enough, and having that torque wrench clicks means that it has definitely reach torque rather than just hoping that it has. I'm still convinced that the largest contributing factor to the failure on the F-100 was the wear on the drum face around the stud holes, raised edges around the holes prevented the spacer from seating properly, then the softer aluminum allowed it to conform and loosen up the lug nuts.

I kinda figured torque would be important, probably more important on the spacers than even the wheels. Plus with most of the spacers being aluminum, Ugga-duggas are not your friend. My real concern was reviews saying they used a torque wrench and stripped or broke studs or lugs before hitting spec. There was a few reviews for a few of them that mentioned that. If you can’t even hand tighten them reliably, that’s a real concern, especially when it goes in for inspection because you know those animals like their impacts for everything.

Could be better, could be the exact same thing in a different box. Before buying I went in search of a better option than the eBay specials. Searched up what people reviewed as being good outside of amazon/ebay. Honestly, the majority of what I found looked like the same spacer with a different label on the box, and the webpages didn't install any better opinion of the product/seller than the Amazon/eBay listings did. The few that did appear better put the price well beyond what I could stomach to pay. Spacers were never intended to be a perminent solution where I used them.

Yeah, that was my big concern, they all look the same but some have decent reviews and some have some major concerns about quality and when YHWX company has bad reviews and XHHR company had good reviews but both look like they came from the same factory, I have questions. (I pulled those names out of the air, but if you go on Amazon, you see a lot of that sort of thing as I’m sure you know).

On the F-100 the spacers were installed to determine if I wanted to acquire and install a wider rear axle. I most definitely do and it was worth the $40 to make that determination.

For the Ranger it was intended to help decide on fitment and to make the 18" Explorer wheels usable until I could get spend on aftermarket wheels. Again, worth the expense. I just didn't both to remove them when I switched from the Explorers back to the stock wheels. Once we get a solution to the control arm problem it'll be going back down and the Explorer wheels will go back on until I get the aftermarkets.

See, I want to make sure I have a good quality spacer because I intend to run the Explorer rims and not go aftermarket on the rims because I want to preserve some of the ”sleeper” aspect and aftermarket rims don’t quite cut it for me.

Are you trying to achieve the same outside edge position or the same center line position? If you want the face of the wheel to sit in the same spot, you probably want a 1" spacer. If you want the center line in the same spot, the 1.5" might be about right.

This link can help visualize offsets and spacer sizes. https://jr-wheels.com/et-calculator

stock vs Ex 18x8 w/ 1" spacer
View attachment 119955

stock vs Ex 18x8 w/ ~1.5" spacer

View attachment 119956

Actually a 32mm spacer would have the center lines of the wheels match, that converts to about 1.25 inch.

A 20mm spacer would make the faces match, that converts to about to 3/4 inch, but may be too thin for a bolt on spacer. They do sell them, but would probably require trimming the wheel studs.

I did a bunch of measuring and comparing. Seemed to me that the backspacing on the Ranger rim I have and the backspacing on the Explorer rim I have is almost exactly 2” different. Since the Explorer rim is supposed to be 1” wider, to get the center line of things to match up, I need to take a half inch (half of the width difference) off the thickness of the spacer which puts me at 1.5” with my measuring calculations. The sidewalls on my 31’s stick out more than the sidewalls on the tires on the Explorer rims, but overall, the width of the tires is pretty close to equal. Since I’m not rubbing anywhere except the fender liner because my tires are too big for how much I’ve lowered it, my thought was if I put the Explorer rim centerline where it is for the Ranger rims, everything should clear and hopefully the smaller diameter tire stops the rubbing. The current tires on the Explorer rims are I believe 245/something which should be a 29.6” tire around 9.6” wide if I remember correctly. I’d like to go to a 255/55-18 which would be essentially a 29X10-18, so similar width to my 31’s but smaller diameter.

Now, other thoughts…

Last night right before falling asleep the thought occurred to me to check some of the fabrication companies like Barnes and Ballistic Fab. A check this morning says Barnes and RuffStuff don’t have anything. 4WheelParts has a variety (Rugged Ridge, Rough Country, Synergy, etc). Ballistic Fab has a set that they claim is 100% USA made and cheaper than the ones Summit sells, but the only offering they have is a 1.25” so I either need to ask them if they will make a 1.5”, or do some more looking, or just accept the 1.25” over the 1.5” that I think I need. I wanted to stay as wide as I could without getting into fender clearance issues, but I’m not sure how much losing 1/4” on each side will really matter.

I’m also kind of curious as to how my measurements indicated that to get the center line correct to put everything in the same spot says a 1.5” spacer but that calculator thing says 1.25” to line up center line. I quadruple checked my measurements and then got dad involved and we both agreed that 1.5” should be correct for centerline Not sure what could have been overlooked.

 

[JoshT]

See, I want to make sure I have a good quality spacer because I intend to run the Explorer rims and not go aftermarket on the rims because I want to preserve some of the ”sleeper” aspect and aftermarket rims don’t quite cut it for me.

I get it. I'm kind of the same way with the build overall. I'll draw a line at wheels though. I figure that those are a common "Day 2" modification and don't really throw off the look in my eyes. Now if you're throwing some big meaty slicks in the rear and skinnies in the front it would be a dead giveaway. What we're going for is similar to a stock 2wd diameter tire on a larger wheel. At least that's what I think we're both going for. Take the 4wd stickers off and a casual observer won't know the difference between it and a regular 2wd.

IMO if you really want to keep it sleeper, stick to a stock 16" wheel. Once you're stepping up to a 17 or 18, it doesn't matter much if it's stock or aftermarket. They are very common aftermarket wheel sizes, lots of otherwise stock vehicles are running an aftermarket wheel. Lots of otherwise stock vehicles are running aftermarket wheels in general. It is the easiest and largest visual change you can make to personalize a vehicle.

I'm not sure, about the differences in measurements on spacer. I don't know your math, and don't really want to think about math right now. One thing that comes to mind is that offset is measurement from wheel centerline, it does not account for the bead lip and does not care about wheel width. Backspace is measured off of the inside face of the wheel and definitely considers bead lip. Bead lip is not included in specifications for wheel width, that's bead seat to bead seat, and thickness can vary from wheel to wheel. I think that is part of why industry standard has moved from backspace to offset. and bouncing between the two can introduce errors.

Since your goal seems to be matching up wheel centerline, I don't think you'd really be wrong with 1.5 or 1.25 inch spacers . One might not be perfectly centered, but close enough is probably plenty here.

I'm 99.9% sure that you'd clear everything inboard with no spacer at all but extreme wheel lock. Even a thin shim spacer would have you clearing everything at lock. That said, it has been a year since I fit them on dad's truck to test.

As for outboard, my truck currently sits with 30" tires on stock Ranger wheels with 1" spacers in the front. No rubbing. We both want to go lower, but by the time you install a smaller tire and a pull it back inboard an inch, you won;t have any rubbing.

 

[4x4junkie]

Spidertrax and Bora are the two brands of wheel spacers you want to look at, and should be properly sized to fit over your hubs. Anything else is likely chinese and/or made of too-soft aluminum.

Both have sizes that the other doesn't (Bora makes some in 1", where Spidertrax doesn't, Spidertrax has some 1.25" where Bora doesn't, and so on), so check both brands if you're looking for a specific size.

 

[lil_Blue_Ford]

I get it. I'm kind of the same way with the build overall. I'll draw a line at wheels though. I figure that those are a common "Day 2" modification and don't really throw off the look in my eyes. Now if you're throwing some big meaty slicks in the rear and skinnies in the front it would be a dead giveaway. What we're going for is similar to a stock 2wd diameter tire on a larger wheel. At least that's what I think we're both going for. Take the 4wd stickers off and a casual observer won't know the difference between it and a regular 2wd.

IMO if you really want to keep it sleeper, stick to a stock 16" wheel. Once you're stepping up to a 17 or 18, it doesn't matter much if it's stock or aftermarket. They are very common aftermarket wheel sizes, lots of otherwise stock vehicles are running an aftermarket wheel. Lots of otherwise stock vehicles are running aftermarket wheels in general. It is the easiest and largest visual change you can make to personalize a vehicle.

I thought about aftermarket rims. I also thought about 16” rims over 15” rims, but between how squishy the tires are on 15” rims and how loud the exhaust ended up, I feel like I need to preserve something. Stock 18“ rims is it. If I hate it later I can always do something else. Part of the whole desire to go lowered AWD was to be sleeper-ish and big slicks out back and skinnies in the front is not the way to do that. Stock looking size looking tires is the ticket there. I can still get to a 10” wide tire, a 29-30” diameter tire 10” wide on an 18” rim. Should be plenty of traction. I’m probably going to run an all-terrain pattern, but we’ll see. I kind of want to lose the stock fender flares and 4x4 decals so it does look more like a 2wd.

I'm not sure, about the differences in measurements on spacer. I don't know your math, and don't really want to think about math right now. One thing that comes to mind is that offset is measurement from wheel centerline, it does not account for the bead lip and does not care about wheel width. Backspace is measured off of the inside face of the wheel and definitely considers bead lip. Bead lip is not included in specifications for wheel width, that's bead seat to bead seat, and thickness can vary from wheel to wheel. I think that is part of why industry standard has moved from backspace to offset. and bouncing between the two can introduce errors.

Since your goal seems to be matching up wheel centerline, I don't think you'd really be wrong with 1.5 or 1.25 inch spacers . One might not be perfectly centered, but close enough is probably plenty here.

I'm 99.9% sure that you'd clear everything inboard with no spacer at all but extreme wheel lock. Even a thin shim spacer would have you clearing everything at lock. That said, it has been a year since I fit them on dad's truck to test.

As for outboard, my truck currently sits with 30" tires on stock Ranger wheels with 1" spacers in the front. No rubbing. We both want to go lower, but by the time you install a smaller tire and a pull it back inboard an inch, you won;t have any rubbing.

That’s pretty much what I figured, but good to have some confirmation.