Hey guys, I have a quick question and I pretty much such at using the search, and can't find what I am looking for.

Currently I am running stock tires (245's, or 30ins). I was thinking of putting on 285's (33's). I know that is the biggest I can go with out rubbing, but what I want to know is how much will the bigger tires kill my MPG? And would I have to change the gearing because of the bigger tires? I am running 3.55 right now I believe.

Basically, if I run 33's, will I see a big differance in MPG's, and if I run 33's will it mess up my gearing at all? Oh, and will it mess up my speedo at all?

Thanks!

 

This is a tire size calculator I found a while back and keep going back to for such questions...

http://www.miata.net/garage/tirecalc.html

 

I ran 33's for a while with 3.55 gears.....changed my speedo a little and actually seemed to improve my MPG when on longer trips on the big road. I found it really bad on fuel around town and was horrible in the mud . I now run 35's with 4.56 gears....and it's great ! Hope this helps some .

 

285's (32.8) are just barely ok on 3.55 i run them because i'm too cheap to spend 1000-1500 or more on gears.

they throw off your speedo and odo pretty far, and if you don't correct it, you'll under report your mileage and actual mpg. if you do correct with superchips, it moves your TC lock and OD out where it should be.

don't call them 33's because a true 33 is something like 33x12.5 which is 34 inches tall and they'll rub like hell.

i get 13-14 around town and 15-16+ at modest highway speed

 

Im running 285 all terrains with original gears, and getting an average of 13 mpg, usually 16 highway 13 city. Got pulled over doing what i thought was 70mph in a 55 with the cruise set, cop said i was doing 65. Not the most exact scientific calculation but i figure the tires put your speedo 5 slow...

 

Okay great guys. Thank you for the information. I will have to get a programmer to change the speedo before I get the tires. I wanted to get a SCT, but they can't fix the speedo yet, which is kinda lame.

 

I like that Calculator, thanks.

 

With your rims, 285/75/16 tires will rub the control arms in a full lock turn.
There should be a square head bolt on the steering knuckle that you can crank out a turn or two and it will keep you from being able to turn the wheel far enough to scrub the tires. Then again, you're in a salt state, so good luck turning that bolt.

 

Yeah salt sucks, its like the black plague.

I do want to get new rims at some point. And a 3in lift. All I need is money!!

 

Get a job you bum.