Good replies, and thanks for the input. As I said, I'm not asking whether I should do it or not, but what you think about it. That's why I've been sitting back and reading not really replying.
I did something similar with my tires. It had 265's and I dropped it to 235's.
Basically a 7% difference according to an online tire guide.
265 what to 235 what?
Those first numbers only tell a width, need more of it to extrapolate a height. Just going to a narrower tire can result in lower rolling resistance and, as a result, improved fuel mileage.
If your stock tires were 29" and are now 32" then your 4.10 Ratio now "acts like" a 3.73 ratio
If you changed to 3.73 ratios in BOTH front and rear axles then 32" tires would "act like" 3.38 ratio
29" tires would be 3.73
If you ran 34" tires now, the 4.10 would "act like" 3.50 ratio
People with larger tires go with 4.56 to get BACK to 4.10 ratio, lol
if you go from 29" to 32" tires a 4.10 "acts like" 3.73, a 4.56 "acts like" 4.10
Honestly I don't recall what the stock tire size for this truck was, been a long time since it had stock sizeand since I paid much attention to the information label in the door jamb.
I understand that people going to 4.56 with larger tires is to get back to the same overall gear ratio, but not everyone goes to 4.10 simply because they went to larger tires. I've seen quite a few people doing it just so that they could spin the same size easier. Burning rubber isn't really something I care about doing, it gets expensive and I already wear them out fast enough in the stuff I drive often. They tell me I like taking curves a little too aggressively.
So what you're saying is that on 3.73 and 29-30" tires, my truc will act about the same as it did with 4.10 and 32" tires? If so, I'm good with that.
If you own a 3.73 rear end I'd stick it in there and try it- just don't use 4x4 until the front is swapped, too.
If you have to buy gears, bearings, etc, it'll take quite a while to offset the cost with gas savings.
That's the plan.
This isn't about gas cost savings, if that were the issue I'd have gotten rid of several vehicles quite a while ago, this one included. I also don't intend to buy new gears. I've got the rear axle that will bolt right in. I've also got an Explorer Disc axle in 3.73 LS if I wanted to convert it, but I don't need 31 spline or discs for this truck and I'm still hoping I might use it in another project down the road. If I like the change I'll buy a used 3.73 front diff from the junk yard or someone parting a truck. The plan is to convert from plastic locking hubs to live axles and, IMO, swapping the diff won't really be much more work.
Speedometer changes with tires size, only the 1998-2000 Ranger used that ABS sensor for speed
That's one part I've thought about but haven't looked into yet. I need to dig in and see if ForSCAN can be used to correct the speedometer on this year model. I've got it and the OBDII adapter for datalogging my F-250, but haven;t playewd with it's more advanced functions yet. Worst case I'll make a mental note of the difference and use GPS on longer trips where I really need to keep an eye on it.
has a '99, so in that magic range. Anything else, changing ratio and/or tire size impacts speedometer.
Note: 7.5" VVS has 102 teeth; 8.8 has 108 teeth and if you want to install a 9.75", its VVS would have 120 teeth. Important when swapping axles in '98-'00 Rangers as that messes with speedometer too.
FWIW most of the axles I have are 8.8s. The 4.10 one in the truck, the 3.73 in the 4.0L parts truck, and the 3.73 I got from an 5.0L Explorer for another project that hasn't happened yet. Have got 2 7.5" axles but they don;t even have provisions for a tone ring or sensor.
Best way to improve MPG is skinnier and light tires, less friction less weight
Lower it closer to the ground to prevent DOUBLE air drag as much as possible
As said previously this isn;t all about MPG, but something like that is in the works. Swapping the axle is going to be part of getting it closer to the ground. Currently sitting on Explorer springs and lift shackles with the torsion bars cranked to match. I'll be going back to stock springs and shackles w/o lift blocks, those will be coming from the donor along with the axle. Torsion bars will be turned down to match.
Tires will be addressed when these get closer to worn out. If I've got room to get it lower, the next tires might be shorter too, but I'll know more after the first stage.
Yeah, mileage is a hard one to gain, I've played with a few tire sizes on my '97 and the only thing that improved the mileage was passenger tires over LT or winter tires...
Unless you're cruising over 65mph often I don't think you'll gain much in mileage going from 4.10 to 3.73, but hey, if you have it try it
Mileage isn't a driving factor, but also a gain I wouldn't turn down. FWIW passenger tires are likely on the horizion once the current ATs wear out, but that'll be a little while as these are still fairly fresh and I've got other stuff to spend the tire money on right now. Since new tire will also come with new wheels, I've got some other stuff including cosmetics that I want to tackle before I start making wheel choices.
I don't live in town and typically bypass the city when driving to and from work. The main places I go are work and hunting club. I've got a 30 mile commute to work and around 120 mile round trip to the hunting club. Most of my driving is interstate and highway. and for the majority of those highways if you're driving 55 you're gonna get run over. So yes, I spend a lot of time cruising at 65+. Also yes, I can easily watch the gas guage drop as I'm booking along in the other truck. Especially the F-100 even though I hold back and make traffic go around me.