Tire for 97 XLT 4x4

[James Morse]

215/75R15SL OWL All terrain was the stock 4x4 tire
on the XLT if you got group 867A (I have that) you'd get 235/75R15SL OWL A/T and that's what I have on right now
optional on XLT was 265/75SL OWL A/T

so I can put on the optional tire, it'll be fine, and it'll still be OEM and who knows it might have had those to start out with I don't have the door tag so I don't know
I am trying to get the sticker for it

this puzzles me: 265/75R15 have diameter 30.7 (so it's basically a 31" tire) and when you go to 235 or 215 that's quite a difference and I'm wondering if they just let the speedo be a little different for them all or did they put a different speedo gear or what? let's say mine is calibrated to 235, and I go 265, it's about 3% different diameter so my speedo would read just a bit low, probably not enough to worry about.
I'm thinking they either used different gears or chose for the most common.

Toyo Open Country A/T III | P265/75R15 (tirerack.com) would be an example of something OEM size
if I go to 31" I think the selection is greater even though those sizes are not appreciably different (265/75 vs 31x10.5). 31 wouldn't have been offered as OEM though.
I'm not saying Toyo is good tires I don't know but I do see it says it's good in snow so for me that would be a plus and it looks pretty aggressive for off road
The more aggressive treads will have a little more road noise I think. The Cooper Discover RTX's that are on there now are quiet, but they're probably a bit less aggressive than I want.

And I'm checking the other tire recommends/un-recommends already made. Thanks.

 

[lowspeedpursuit]

Axle gearing. Trucks that came with the biggest tires all had 3.73s. All other things being equal, 235/75R15s with 3.55 gears and 265/75R15s with 3.73 gears will have a negligible difference in speed vs. RPMS.

If you go from 29"s to 31"s on the same gears, your speedometer will read 5% slow unless you compensate at the speedometer gear (as much as possible).

 

[lowspeedpursuit]

I have 3.73.
I can't be sure mine originally came with 235's but really it doesn't matter because 265's were a factory option for the truck. There was no 4.10 afaik.
Right but I'm only thinkinbg of going from 28.9" to 30.7" that is 1.8MM or 1/16"
With 3.73 going from 235's to 265's really shouldn't matter much. I figured it at 2.8%.
There had to be some kind of matchup between the tire size and speedo but I see what you are saying. Probably this info as to the gearing is on TRS somewhere.

Sorry, that wasn't really a comprehensive answer, just adding a "missing" piece to what you were already speculating. You're correct that different trucks can come with different speedometer calibration.


The driven gear on the sensor is color-coded and has 16-21 teeth, and you can also buy 23-tooth gears that I'm familiar with. '98-'00 use the rear ABS sensor for speed, but electric speedometers start in '95, so I assume in '97 you have the option of changing the gear or exploring electronic correction. When you adjust the gear, you won't necessarily get it perfect; you're just getting as close as you can.

I'm not 100% sure what's going on with your units? The difference between the diameters of 28.9" and 30.65" is 1.75"; it doesn't get converted to mm. Uncorrected, your speedometer will read something like 1.75/30.65 = 5.7% slow--maybe not exact because we're rounding off those diameters. Your axle gears don't affect the amount of miscalibration. Oftentimes, vehicles will deliberately "overestimate" speed on the stock speedometer, basically making you drive a little slower than you think and "erring on the side of caution". As a result, you may find that with a modest increase in tire size, your speedometer ends up dead-nuts GPS-accurate, because it was actually fast before.

In any event, the speedometer is only one of the things that comes into play when you increase tire size. You're going to be turning lower RPMs at the same speed, which is generally viewed as a decrease in "power". For a given vehicle, there's a range of tire diameters which function passably for given axle gears. Outside of that range, you will want to regear. Conventionally, IIRC 4.10s are considered "optimal" for 31"s, but 3.73s are also fine.

Brand-wise, I don't love Coopers. I have Goodyear Wranglers. My other vehicle has General ATX.

EDIT: I don't know what happened to your post, but I'm not untyping all this shit.

 

[superj]

i bought some 30" mud tires for my wranger. since the wrangler and the ranger have the same bolt pattern, i put them on the ranger, just to see how cool it would look.

the ranger has the 235/75/15 tires on it originally and the new tires put my speedo exactly on what my gps read

 

[James Morse]

btw my post you quoted which I deleted as soon as I realized it was wacko the diff of 1.8" I was mixing mm (tired I guess). I see you found the error and you are correct of course in your numbers.
When tires wear the diameter changes a little (then if it was calibrated perfect with new tires it'd read a bit low with wear, but I'm nit picking)
superj are you saying your Ranger with 30" tires reads exactly correct? That's interesting if so.
there wasn't a 4.10 available in 97 otherwise that would be nice with 31" tires.
sorry about the post I should have edited it, I was in the shower and was thinking wtf did I just write and was too tired to edit so I trashed it.

since 265's were an option on the 97 (without 4.10) I have to believe Ford thought the power loss was acceptable. I realize it'd be something, but the 4.0L has lots of power, I think I'd be ok with it.

I'd like to get a gps reading. Are you doing this with your phone or a more sophisticated setup? If I knew that then I'd know the effect of things.

If I had the freaking door jamb sticker that would have told me what the truck was wearing new and likely was calibrated for that. All I know for sure is it would not have had 215's because XLT 4x4 got at minimum 235's then the 265's were an option... and as a factory option they would have put whatever they felt was correct for 265's with 3.73. And it would have been plastered on the door jamb, the tire size OEM.

Let's say the reading is quite a bit off (say I put on bigger tires and do nothing to the gear). I can change the speedo gear, right?

I don't know if it's possible to change my rear end to 4.10 but if it is possible, that might be an option. I imagine that is a bit of work. I know race drivers use a huge range of rear end depending on the track, of course they have lots of money and crews. If you do that does it affect the front at all or does it make the front 4.10 as well or how does that work? Would I have to change 2 gears?

Basically I want a fairly aggressive tire and I suppose I could do that and stay w/ 235's, if that's the calibration now. What would probably help me most at this point is a) GPS reading and b) door sticker so I know what the truck came with. It has to be either 235's or 265's; I supsect 235 but it's an unknown.

I've been bugging the dealer where I got it to get hold of Ford and get the sticker. No results yet.

To add to this mix, my spec for clearance is 7.9". I'll assume that was with a 235. Putting 31" would raise the truck 1/2 of the difference or 1", isn't that true? So really the clearance would be like 8.7", I think. Adding the inch height would be a good thing. And they look better, I think. So I'm really inclined to go that way.. There's no mention of increased height so maybe they just assume you would figure that out.

thanks, and sorry about that mixed-up post my bad

 

[lowspeedpursuit]

No worries; I thought I was losing it, but figured I'd leave my post up for search purposes--or in case I'm thinking something stupid, so someone else can correct me.

To test my speedo, I stick my phone in my cupholder with a GPS app running. I'm not sure what the "best" app is; I just use whatever. Yes, if you get bigger tires, you can put in a different speedometer gear.

If your door jamb sticker is missing, stock gear ratio and spring capacity are given by the vin decoder. Are you pulling your 3.73 ratio from there, from an axle tag, or from doing the math? It doesn't seem to show stock tire size, but I think you're overthinking the importance of that info. What matters is whether the tires you want fit, you have the power to turn them, and to a lesser extent how to correct the speedo, and you can sort all that out without knowing the stock tires.

I'm not the authority on this, but one of my parts trucks was a '95 (same sub-generation) with 4.10s stock, so I don't see why they wouldn't be an option in '97. But, again, what was available stock isn't really important. What matters is what you want to do, and what's available now.

I don't know if it's possible to change my rear end to 4.10 but if it is possible, that might be an option. I imagine that is a bit of work. I know race drivers use a huge range of rear end depending on the track, of course they have lots of money and crews. If you do that does it affect the front at all or does it make the front 4.10 as well or how does that work? Would I have to change 2 gears?

It's not realistically possible to change your gears to 4.10 right now, because that ratio isn't available for your front diff unless Yukon decides to start making them again. Unless you pull junkyard gears, your gearing options are what's in there now, and 4.56-5.13.

Really, I think most people will agree that the 4.0L with 3.73s will turn 31"s well enough to leave it alone. I wouldn't overthink it.

 

[James Morse]

Ah, I got 3.73 from fastpakr I gave him the axle tag numbers

VIN is 1FTCR15X2VTA66604

VIN Decoder - Ford Truck Enthusiasts Forums (ford-trucks.com)

I think some of the eq has to be taken with a grain of salt (not the major stuff) but pretty much it looks right. For instance color, or tires, that's not in the VIN (but it's in the door sticker which I don't have).

Springs are two stage rear according to the decoder, I have no idea what that is. I have the rear spring numbers in another post I'll try to find them (read off the springs)

Yes I agree seems like 4.10 should have been an option. I'm going by the Ford brochure and don't see them but maybe if you asked you could get it.

97 brochure is a little sketchy in terms of, you could get OEM roll bar or tubular bumpers, but you don't see them in options. So it could be likewise for the 4.10's.

That's totally weird about 4.10 not being available then the huge jump to 4.56 and up. Those might be good for off road but it would rev way high on the street I think.

I agree it can be overthought and I'll run gps on it (phone) and see what that says relative to speedo that's at least good info that I'd want to know in any case.

 

[superj]

i used a gps app on my phone to check my speed. and you will have to change the front diff, if 4x4 and changing the rear diff to 4.1.

i think my 04 is 4.10. i would have to get under and check again but i think thats what it has. its nice to drive and going to the larger tire was not noticeable when driving around town that day i had it on. the only thing i noticed was the tire sidewall was more flexy so i felt the truck had more "slop" on the highway.

 

[lowspeedpursuit]

If we start talking about 3rd-gen trucks, it's worth pointing out that '98+ SLA front gears are still available in whatever ratio. Someone else may chime in to correct me, but my understanding is that while the carriers are different, the gears themselves are actually compatible with the Jeep D35 rear, which greatly broadens the market. For example, USA ZGM35 gears list both Jeep and Ranger fitments.

'90-'97 D35 TTB gears are HP, reverse-cut, and are the ones which are rapidly disappearing.

 

[superj]

i wonder if those are the same as jeep, too? some jeep are hp reverse cut too. my 87 cherokee was that way on the front axle d30

 

[lowspeedpursuit]

So I learned last week (I think in another topic by the same poster, actually) that D30/D35 apparently have similar axles, but they don't use the same gears. I'm not familiar with another reverse D35 besides our TTB. Wikipedia says the D35 front appears in the '97-'00 Dakota/Durango, but it's standard rotation like the later Rangers.

The only D30 part I have working in my diff is the oil baffle, and I suspect it's actually slightly thicker than the D35 baffle should be.

But, I feel bad getting too caught-up in gears at the expense of OP's question about tires.

 

[James Morse]

Gears: so 97 has an oddball reverse cut gear. I'm wondering if it's something that is of a price (after finding) that I should just get one/them to have on hand?
Tires: True about larger sidewall is going to be more slop on the highway.
I could go to a 265/70R15 that would raise the truck only slightly and a little less sidewall. Basically that's a 30" tire so you could go that way it is really equivalent. It would be a more aggressive look/performance without looking huge.
Just wondering if 31" is too big yet the optional tire 265/75R15 is basically a 31". It would raise the truck an inch.
First thing I am going to do is get a reading from gps and see current calibration on the speedo then I'll know the effect of changing from the existing 235/75R15. Which are 1/2" smaller diameter than new as I figure it as they have just over 1/4" of tread and originally they should have 1/2". So I should take that into account. I suppose you could measure the actual circumference but that's probably going too far with it.

 

[sgtsandman]

My experience with Rangers, if everything is factory, the indicated speed is about 2 mph faster than actual traveling speed. Since you are still figuring out some things on the truck, what yours will actually reads might be different.

When I switched to 31” tires from 235/75R15 (29”), I went to 2 mph slower travel speed than indicated.

If I remember correctly, you can fix the indicated speed by changing the gear in the transmission with your year.

Going to a 31” tire is going to reduce the get up and go with 3.73:1 gears in the axle. Here in the Appalachians, it makes a difference. Where you live, it might not make much of a difference. You can still off road with them, lower gearing would just be better.

4.56 is a good range if you off road, tow, or haul a lot but that is a call you are going to have to make.

Also, keep in mind that there is going to be a fuel consumption penalty with bigger tires, even if they aren’t all terrain or mud tires. I saw about a 2 mpg drop on average with the swap.

 

[James Morse]

Thanks sgtsandman I haven't done the GPS yet but I'm going to do it.
That's why I was thinking maybe a 265/70R15 would be not such a huge jump, just a bit smaller than the optional OEM size.
So it would raise the truck just a little, and it would change the pep a little, and the mph a little, but none of those things drastically.
Seems to me even though 265/70R15 isn't a stock OEM choice I don't see what would be wrong with it.
Later Mazda and probably Ford had 16" wheels with the larger tires but there are so many things different comparing '97 to say '06 that's I suppose pretty irrelevant.
If I ever changed to 4.56 that would be the time I'd definitely want 31". Truck would rev higher on highway of course. I have a chart that can tell all that.
I don't think you get into any issues with steering rub going to larger (within OEM) would you? I'd assume not.
What should my Cooper Discover RTX be inflated to? (missing door sticker)

 

[don4331]

OK, a few things:

This is Rangerstation; '93-'97 is 3rd generation, '98-00 is 4th and '01-11 is 5th (no matter what Wiki says)

'97 4wd Rangers came with 3.27 or 3.73 gears from factory.

But if you look here: https://www.therangerstation.com/tech_library/pdf_documents/Dana_Ford_35.pdf you will see some other years that have alternate ratios. If you want 3.55 or 4.10s they're out there.​

Swapping to 4.56/4.88/5.13s is possible, but will be seriously expensive - as truck is 4wd, you have to do front and back at same time, as it has been 25 years since any OEM used the Dana 35 high pinion parts are rare.​

(Personally, I would suggest a doubler or lower transfer case gears, before going to 5:13s.)​

​

When Ford assembled OPs Ranger, they specified a transfer case with correct gear on output shaft/speedometer shaft to match tires and gear ratio, so it would read correctly (actually little low, so you don't get ticket when driving just a little over). If @James Morse changes tire and/or gears, he should pull the transfer case apart and replace the gears with correct ones. In all actuality he will probably just use phone gps for speed.

Its not just diameter difference, but weight that changes performance. Goodyear 235/75R15 Trailrunners weigh 29 lbs; Cooper 265/70R15 Discovers are 39lbs. That's 33% more weight to acceleration from every stop, same to stop at every red light.

Contact an autobody shop about door sticker, you'll have more luck. If your door doesn't have sticker, it probably means door was replaced (SuperCab doors often have sticker on cab). Autobody shop is supposed to replace the sticker as part of the repair, so they can get them efficiently.

2 stage springs means you have couple/three long thin leaves that are curved and more/less go from shackle to shackle (main leaf does go from shackle to shackle, lower ones become progressively shorter), and one thick one that is more/less flat. During daily driving, the long, thin leaves give you decent ride, when you haul a heavy load, the thick leaf keeps axle off bump stops so you still have a little suspension.

An F-350 or F-250 Camper special would have 3 stage leaves, lots of long thin one (thin is relative, we're talking 1 ton here), an "overload" leaf or 3 (shorter than main leaf, spaced off above the main leaves, with their own bump stop) and the last resort thick flat leaf. This allows relatively smooth ride unloaded, able to carry "normal" load while still having majority of suspension, yet keep off bump stops at legal limit.​

OEM roll bar or tubular bumpers we dealer accessories. I have I think '94 Dealer Accessory brochure and they're in there.