You will probably get better fuel mileage if you go with Low Rolling Resistance tires. I took some of these LRR 17" tires off my new truck and replaced them with regular 20" non-LRR tires and the fuel mileage dropped from 22 to 19. Don't listen to the quacks about circumference being the only thing that matters. The stiffness of the sidewall as well as the "squirm" of the tread matters very much also. Try to get tires rated by the D.O.T. as Low Rolling Resistance.
thumbs to C.B.
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we don't know the vehicle in Q.
as a rule of thumb.
trucks,
they rely on torque. going 1 maybe 2 inches over stock in overall wheel/tire radius can see some hwy and city mpg improvements *if* driven gingerly. the least bit of agressive driving and mpgs will suffer greatly. since it it a utility vehicle, it's utility service will likely suffer in all cases. as final gear ratio will be effected.
cars,
same goes for cars for mpg improvements. but more like only 1 inch overall. as they don't typically offer much in the way of torque. not their forte'.
fitment is a factor for all platforms.
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word of caution.
on some/most of the newer platforms, an automatic transmision equiped platform maybe totally skewed. those that employ shift soleniods, computer monitoring of that, in conjunction with speed sensors or output shaft sensors. as not only shift points are monitored, but a computer may also use that info to determine best fuel mixtures and dynamic timing. so may not be the best thing to do on those types of platforms. one would check with the dealer for possible issues doing that.
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EDIT, since "comments" is unavail at this time,
@ anotherredman,
no thumbs from me. but i didn't see where anyone said that circumference was the "only" influencial aspect. reffering to anyone of us as "quacks" when some of us are certified, is a little harsh.
lrr tires are another influencial aspect. but over-all wheel/tire radius is much more influential. and, some ppl don't care for those lrr tires as the side walls on those are stronger and typically employ a harder compound. lends a rougher ride to some ppl. to compensate for that, ppl let a pound or two out of the tires. in that scenario, the lrr aspect is compromised. my comment was not intended to invalidate your reply. merely trying to help.
It's a 1992 Ford explorer 4.0
If you use a larger diameter rim with a low profile tire the overall diameter will be the same.
Rim diameter doesn't mean squat. *Tire circumference does.
Problem is, you absolutely have to make sure it'll fit your car. My tire size if 205/55/16 and I'm looking for all seasons and can't get anything because it's 15s or 17s ...
Right now I'm running 235/75/15 and I'm wanting to go with 18s
