I have a '94 Ram 1500 4x4 with BFGoodrich 285-75R-16 Mud Terrain, which
are great tires by the way. Yes, going with bigger tires will throw
off your speedometer reading, so you should have it adjusted by a shop
(I think it's the law, although that choice is left to you). I haven't
had any issues with gearing or transmission problems, but the bigger
tires give slower acceleration (if you care about that) and add weight
and are less aerodynamic (assuming you will be getting tires with an
aggressive tread). On the plus side, they look awesome and fill out
the wheelwells better, and make the truck sit up higher.
Thanks for the input......I really don't care about the speedo.......I
don't really drive all that fast anyway, but my main concern was that
they don't affect anything important....and you're right, they will
fill out the wheel wells a lot better than those little 245's.....one
last question; I also have the stock rims, and I've heard that some
tire stores will tell you that they won't put a larger tire on a stock
rim....is there any precautions with that, or is it just a tire dealer
preference?? Thanks for helping me out....
I have also heard that because they don't want to deal with messing up
people's vehicles and then something going wrong and then suing them.
I think that is mostly larger nationwide chains that have policies like
that. You will most likely have to check with smaller, privately owned
tire shops for the best chance that they'll install whatever you want.
Yup, just found it. OEM is 245-75/16 with optional being 265-75/16
or 275-70/17. So 285-75/16 is closer to OEM diameter I do believe.
Your speedo should read slightly higher than OEM and going to the right
size will bring your RPMs down slightly for the same speed.
Ok....ran the numbers....the tires you are running are 3.3% smaller
than what is OEM (not optional equipment). The tires the other
truck were running are 7.8% larger. A lot bigger difference than I
thought it would be.
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