Have any of you that have upgraded your wheels to larger sizes had your speedometer settings changed to match your wheels? I was under the impression that the main reason that you had to stay within the original tire/wheel diameter was so you wouldn't throw off your speedo readings. But searching around the net I found products that let you reset your computer's settings to match your new wheels and that this was required by law.

I hadn't read anything on this board about anyone doing this. I'm curious because I was set on getting some bigger tires for my xA and now that I see that I can do this I want to find out how big I can get my tires without rubbing ang hurting my braking.

If you know about this - share it with us.

 

Go here http://www.eunos.com/tirecalc/

You can plus size you wheels correctly so that you don't even have to worry about buying anything. Basically plus sizing is this, when you upgrade you wheel size from lets say 15" to a 17" all you essentically have to do is lower your sidewall. For example my camaro had 245/50/16 tires stock and lets say they were 26" tall w/ the tire and wheel combo when I upgraded to 17's I put on a 275/40/17 in front which is also 26" tall and the rears were 315/35/17and you got it 26" tall SO according the cars speedo and odo nothing had changed.

On the site I gave you above you can try different sizes to see whats the closest you can get. Hope that helps some.

 

You can go an inch larger outside diameter without really affecting anything with the speedometer. On paper it does, but in reality it doesn't.
A tire has approx 13 32nd's tread depth on each surface and given that a tire has two surfaces (top and bottom) that equates to 26 32nd's of an inch. That is almost 1 inch of tread rubber. So from the time that the tire is brand new until the tire is bald it will change it's overall diameter by one inch. If that was an issue, manufactures would issue warnings that once you tires appoached a wear factor of a few 32nd's of an inch you had better replace them as your speedometer would be incorrect resulting in traffic violations. Since there are no such distress warnings you can feel free to know that tolerances are ever present and you are not to worry of 1 inch or so either way.

 

thats good to know i heard some mumbo jumbo about that too