IÆm not sure what my T came from the factory with, but when I got it with 48K miles on it, it had 31X10.50Æs. Based on the mileage, IÆm assuming they were the originals. I have subsequently replaced them w/ 31X10.50Æs. Now since IÆm a cheapskate and want to save every measly penny I can, and since the ownerÆs manual indicates both sizes, can I go with a P235/75R15 rather than the 31x10.5R15. What does it do to the performance, mpg, speedometer reading, etc.?
Oh yea, 95% of my driving is highway.
Thanks for any help.
-E

The size you referenced is considerably smaller than 31x10.5... It's only 29x9. Your speedometer & odometer will register higher than actual (plan on about 7-8 over @ 60 mph).

That said, it will actually help your performance in city driving... You'll notice a smidge more grunt in the low end (i.e. - stoplight to stoplight). But you'll lose overall mpg (especially on the highway).

If you have 31" now, I assume you probably have a 4x4. If so, I would stick to the 31" as smaller tires will mean higher RPM (more gas) as you do mostly highway driving.

If you want to save a few bucks, try to find a tires that starts with "P" with the same overall diameter of 31" that is more suited for passenger cars. The benefit of such is that the tires most likely is lighter, and narrower than the standard 31x10.5/15. The narrower foot print would mean less rolling resistance. The drawback is that you won't be able to carry the heavy loads your truck is built for, and the sidewall maybe weaker if you take it offroad.

Another cheapie idea is re-treads. The re-tread industry has improved quite a bit over the years. Most trucks and commercial fleet vehicles are all running re-tread tires. They offer similar performance, but will save you about 20% or so in cost. Not a lot, but some savings.

Lastly, you can always look under local classifieds for used tires that are factory take-offs. Many people that buys new trucks may want to upgrade their wheels and tires immediately. Sometimes, you can get a very good price on an almost new set of tires.

Usually the sticker on the driver's side door jamb has the original size tires printed on it.

I know my truck came from the factory with 31" tires, but the sticker on the door indicates 235's. So the sticker is not correct if you have and 4x4. I don't think any 4x4's came with 235's.

So that means that the speedometer is off from the start becuase of the tire size change right? So if Im runnin 33's, how far off is my speedometer? (being that it should have been calibrated to the 235's)

My '96 4WD came with 235's. The 31's were optional.
I'm running 31's and my speedo shows about 4 or 5 mph less than actual. I've been running 31's for over 100K and this means my real total odometer reading should be a bit over 200K even though it reads just over 185K.

31s were a no-option option when we got ours. All the DXs in the area had 31s, sort of a no-charge upgrade on the base model.

I have a set of 5 31's (factory rims) sitting in a shed, looking for a new owner. The spare is the original and still has those little nibs on the tread (as in never used).

If in the PA/NJ area, email me if you want to buy them.

(sorry for the plug)

Anyway, they were 31's with the 95 DX. Speedo was not off (it is now with 33's). <img src="/forums/images/graemlins/lol.gif" alt="" />