autoguy said:
I guess what I was trying to say is that you can go UP TO 3% larger or smaller without having an adverse affect on the functionality of the ABS, engine control systems, etc.
Yes, if you put it in a spreadsheet, you can analyze it to death. If you want to get really technical, keep the EXACT same size as OE and then there will not be any problems.
Think about the tires wearing, if you really analyze it, the size actually changes as the tire wears.
Another thing you will see is that different manufacturers have different size specs for the same size tire.
Yes, 3% is a good casual guide. Going beyond it will get you into speedo differences that are more than just a mile or two off and can get you into trouble, or at the minimum have you putting more mile on than you really are.
Yes, I do analysize things to death, I like things in detail so that I know fact from fiction and to judge where I draw the lines of acceptability. If you or others choose to go casual, that your choice.
Correct, as tires wear, it does affect your the size of your tire, but from brand new tread to worn out tread (the 3/32" basis for when to change rubber) we are still talking only about .2 or .3 inches in difference.
I based my calculation of the diameter on the formula for tire ratio and wheel diameter, not on manufacturer's specs. I would assume that there would be some variance between manufacturers, but only slight ones that are within acceptable ranges.