Hi All,

I've picked up some 17" wheels for my 2nd track only set of tires. I know if I mount 225/45's on these wheels, I'll lose ~inch of the tires diameter (compared to stock). Besides an incorrect speedo reading and a similar effect of lowered gearing, what else can I expect?

 

It should feel a bit faster and will be more responsive

 

Wouldn't it be slower because each tire rotation will travel a smaller distance?

 

^So by your theory, An RX8 with 22" wheels would be faster than a RX8 with 18" Wheels...

Lower gearing = Smaller Wheel/Tire = Quicker Acceleration

 

^mine does

 

except it takes more torque to rotate the 22" wheel versus the 18" wheel. So, yes, you do get more distance in one rotation, but it takes more force to get the wheel to rotate that far.

 

and we all know the 8's came with 300 ft/lbs torque...

 

w00t w00t oh....wait....

 

^im busy making some motivational posters... did u see my scream one?

 

nope, where is it?

 

Wheel size != tire size. I was talking strictly tire circumference. (In a condition where weight is not a factor and tire circumference is the only variable)

Speed = Distance / Time

Time is fixed for each rotation - drivetrain won't spin faster or slower if weight is unchanged. Distance is increased per rotation. Thus speed is increased.

If we add the weight variable, then it becomes fun and we get to do a few nice formulas to add up the impact of both variables at different points. I'd love to see someone draw it up but sadly I have other priorities.

FWIW, if you have a heavy 18" and a light 22" that weigh the same, it won't matter. The rim size is NOT a variable in this equation. The only variables are Tire Circumference and Wheel+Tire weight. Depending on the extent of the deltas of both of these variables from the stock setup, either one could have a higher impact than the other.