[Dale E. Mallett]

Hi Folks,

What effects will increasing the wheel size on my car have? For instance: Will increasing the wheel and tire size to a 17" or 18" cause errors in my speedometer or ABS system? If so, what are the recommended fixes? Will the larger wheel size cause problems with road clearance? Appearance wise: Does increasing wheel size have the same effect as lowering the car?

Thanks.

Dale

[shartley]

When you increase the wheel size but don't also adjust for tire size your speedo will indeed be off. You can get that adjusted though.

But if you increase rim size and adjust tire size so that the actual "size" of the wheels are no larger than stock, your speedo will not change.

In case you didn't get that... to increase rim size without increasing overall wheel size you reduce the amount of rubber on the wheel. And most rim/tire places can calculate that for you.

But most folks I see with Mustangs will increase the entire wheel size (rim and tire) to better fill up the wheel wells. And then you do have to remember that your speedo will not be accurate.

However, a lot of us with trucks do the same thing with putting beefier wheels on our vehicles and don't mess with the speedo at all. It is no longer accurate, but we know this and drive accordingly. Larger wheels will make you drive faster than stock when the speedo is showing a certain speed. Usually not a lot, but the difference is there.

ABS... should be no problem.

Clearance (road).... should be no problem. However, you do have to think about wheel well clearance. There are certain sizes you should not put on Mustangs because it will cause rubbing issues when turning or going over bumps. And that has to do with clearance in the wells, not with the road.

Appearance.... going larger in wheel size (as well as more rubber) will fill up your wheel wells better. So in some degree it is like lowering the car. But the "fill" will be more even and look better IMHO with an increase in wheel size. And quite a few folks do both... increase wheel size and drop an tad.

I hope this helps.

[Dale E. Mallett]

Hi Shartley,

Nice answer. I've printed out your response and shall consider it when I do the wheel/tire shoppiing.

Thanks.

Dale

[aowpsycho]

Originally Posted by Dale E. Mallett

Hi Shartley,

Nice answer. I've printed out your response and shall consider it when I do the wheel/tire shoppiing.

Thanks.

Dale

also keep in mind that it is very simple to fix your speedo...it only requires a tuner if you have one you can do it, if not a shop can recalibrate it for you..

here is a calculator that shows what size tire and rim you have and how close to stock your new rims and tires will be...mess around with it its a nice program

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

if it doesnt work click on the older version, you may not have the updated java