235/75R15 vs. 235/70R15

[georgiadevil]

Hey...I'm a first-timer, so I'd like to say hello.
My question is this: I am able to get a really good deal on a set of 235/70R15...I currently run on 235/75R15 and am in need of new ones...what issues (speed, mpg, handling, etc.) am I facing?
Thanks much.

Also, can any of y'all recommend a place in Atlanta to get tires mounted (that weren't purchased at that place)? Thanks.

 

[Lee S.]

try this link:

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

Looks like the tire diameter will be off nearly and inch and your speedo will be 3.2% too fast.

Should work for you though.

Lee

 

[Chew_12]

try this link:

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

Looks like the tire diameter will be off nearly and inch and your speedo will be 3.2% too fast.

Should work for you though.

Lee

It should work. That is wierd that the width affects the lenght. I thought 235 was the height. and the 70 is the width...

 

[georgiadevil]

Thanks, I had checked that out...that means that if my speedometer reads 70mph, I'm actually going 68mph (est.), right? Not 72mph?
What about ride quality? I think I've read that if the sidewall is lower (less air), the ride will suffer.
Handling/cornering should be better, right? Also, I would presume that mpg would improve...granted, negligibly...being lower to the ground, not the other way around. True?
Thanks.

 

[etc]

It should work. That is wierd that the width affects the lenght. I thought 235 was the height. and the 70 is the width...

First number is the section width, the second number is the height, in percentage of the width.

so the height would be 70% of 235 = 164.5

 

[Lee S.]

Thanks, I had checked that out...that means that if my speedometer reads 70mph, I'm actually going 68mph (est.), right? Not 72mph?
What about ride quality? I think I've read that if the sidewall is lower (less air), the ride will suffer.
Handling/cornering should be better, right? Also, I would presume that mpg would improve...granted, negligibly...being lower to the ground, not the other way around. True?
Thanks.

You are correct on the speedo. I really don't think you'll find much of a difference between the 2 sizes handling or mpg. The are so close.

 

[Jason94sport]

As stated speedo will be off a little. It will read faster then your your really going. Actually it might not even change much since the speedo in the X is just so inaccurate anyway. For ride or handling, you shouldn't see any difference at all. Your not really changing the tire size so much. It's only 5mm less sidewall. I would bump up the tire pressure a little if you do get them . About 2-3psi cold from what you would normally have.

 

[georgiadevil]

Thanks, y'all...I really appreciate the advice.
BTW, I dig this site.