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Hi forum,

For the coming track season I am going to use 19" track day wheels and will fit Michelins P4S or Cup2 tires.

I am in doubt to fit 265-235/35 19" vs. stock spec'd 265-235/40 19", reason would be to use the 35 sidewall-% to improve handling...
I do not care about speedo accuracy nor of shorter sprint and lower top speed.
The Cayman has no PASM.

  • steering might become crisper ?
  • a cheap way of lowering the car without fitting coilover springs ? by how much would it sit lower ?
  • what about car's electronics : ABS, ..?
Your advice is appreciated !
 

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Welcome to the forum!

You may want to consider dropping down to 18" wheels for less unsprung weight and more/cheaper tire options.

Dropping the aspect ratio is relatively common on the Cayman/Boxster as well, mostly due to tire availability (usually 245/40R18 + 275/40R18). It does lower the car, and also effectively lowers the gearing (faster acceleration at the expense of lower top speed).

You'd get more change in steering turn-in by modifying the car's alignment, and as far as you keep the front/rear changes relatively equal (i.e. don't do a lower front aspect ratio but keep the rear the same) , shouldn't have any problems with electronic systems
 

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...also effectively lowers the gearing (faster acceleration at the expense of lower top speed).
...
I've often wondered about this... It takes a certain work/energy to get you to 100 kmh. If lower gearing got you there, you'd be doing it with lesser work. Someone with better grounding in physics may enlighten us.

Anyway, to add a data point, I used to own a 2007 Subaru Forester 2.0 NA with low gears. We are talking about 1.6 gearing ratio, not a small difference in circumference. The car felt more agile and powerful, but as hard as I tried to clock 0-100 kmh with my chronometer wristwatch, I didn't get any significant difference, one way or the other. Actually at times I got worst results in low gears, as I had to do one extra shift to get to 100.
 
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