Ideal Offset? 15x7 ET42 Wheels

[TRD_Yaris]

Originally Posted by Ron

the bigger the overall diameter of the wheel/tire combo, the more physical distance the car travels for every revolution of the axle.

so a 205/55/15 tire would net a similar effect as a slightly higher final drive, than say a 195/55/15 or 195/50/15 tire.

fyi, the yaris has a slighly shorter final drive ratio than the older echo

i personally have upsized my tire sizing a bit, to get the taller gearing because i dont really care about the get up and go acceleration of the car, but the difference is may be 4%. so not that much of a difference at all.

yes, this is what is was talking about as far as "overall" gearing being affected by tire profile. What i mean is that : IF your stock tire size is 195/55/R15 (for example), then if you changed over to 195/60/r15 or even 205/55/R15 the then you are actually changing the overall length of travel for every revolution of the wheel/tire..meaning your speedo will be off and even if you got better gas mileage, you wouldn't see it unless you accounted for it

simple explanation: basically, if you took a tape measure and wrapped it around the tire along the tread..you would find the 195/60/r15 and 205/55/r15 are a bit longer than the stock 195/55/r15 's tread length..