i have used the http://www.nwtoys.com/google/ search to help me find experience-oriented testimony on performance depletion after upgrading tire size but not upgrading gear ratios. although i did find a wealth of info. none of it answered the question of mine.

how much loss in mpg, throttle response, take-off speed, rpms, and overall power and efficiency would i be expecting if i put 31 X 10.5 mud terrain tires on my 4Runner (3v-ze,5-spd,~188,000 well maintained,13mpg,4.30 gear ratio)

i am currently running 255/75/R15 GT Road Hugger or something like that on stock rims. These tires are good; they're smooth and actually feel like they grip or 'hug' the road well.

but now im looking to upgrade to mud terrain tires because i'll be mudding

my choices are 235/75/R15 (which is a lot closer to stock tires at 225/R15) mud tires or 31 X 10.5 mud tires (which i really really want)

i would not buy the 31X10.5s if it made me lose 2-3mpgs, and made me do high-rev take-offs more frequently (i must do them now as it is )

reply if you are confident you might help

thanks :]

 

I have 33x12.5 on my 88 truck with the stock 410 gears and a 22re that is stock and it gets about 18 mpg and I don't have to over rev to take off I dont like the 3l, s tho

 

The 3.0L is the issue. Honestly, you won't see a massive drop in mileage. But, don't expect to get much better than 15-16mpg period out of that motor.

3.0L = 4cyl power with V8 fuel economy.

 

I have 31x10.5 Toyo AT/s on my '91 4Runner right now with the 3.slow and if I remember correctly something like 4.10 gearing. I started off with 235/75s on pretty much stock-like rims when I got it and switched to these tires on some black steelies. As for MPG, I did drop a little I think, but as Scotty said, you're just not gonna get much period. The sacrifice was worth it to me.

 

scotty is right.


you're going from roughly a 30x10.50...to a 31x10.50.


in all reality, those 30" tires are prolly closer to 29" and the 31's are prolly closer to a 30"

another thing that factors in is the WEIGHT of the tire.

if you're already getting 13mpgs with a 30" tire and 4.30 gears..then you have something wrong, and your motor is not running the best it could be.

with 31's and 4.30's you'd prolly be seeing about 15 if you drive like a normal person.

 

i drive my truck about 50 miles a day with my 22re and 4.10s and i was looking for a good all around tire size. i ended up going from a 225 and getting around 25mpg to a 30x9.5 tire and im now getting 22-23 mpg.