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Old 07-22-2010, 01:07 PM   #7
Bladecutter
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Join Date: Jan 2009
Location: Arvada, CO
Posts: 229
Quote:
Originally Posted by chris7676
I'm not looking for lap times or ultimate grip - that's why. I'm sure you can fit a 225 on 8.5 rim - Porsche even states this for the winter tyres and people on here have fitted a 225 on the 7 rim although for the fronts. But which is better rim witdth for the tyres ?
Honestly, its going to be a mixed bag, one way or another, as long as the rim width falls into the recommended range.

Like said earlier, the smaller size will lower unsprung weight, and make the throttle feel a bit more responsive, if not lively. The sidewalls will flex more, as the car gets thrown around, and might not feel planted enough.

The widest choice will roll onto the outer edges of the tread, and chew them up pretty quick, giving you a tire that goes away much faster than expected, and overheats, but gives you a stronger sidewall, that doesn't flex much, and allows you to predict when that breaks away more consistently.

The preferred rim size will give you a good balance between the two.

The 225/45-17 is the same diameter as the 255/40-17, as I'm sure you know.
If I were buying winter tires for the Boxster, that's what I would put on it.
I don't know how well you're going to do with getting the power down in a DE with that size, with one tire unloaded and spinning, and the tire fighting to keep control of the car, and heating up rapidly.

Would be interesting, to say the least.

If money's not an object, go with the recommended rim size.
Better to balance everything, than to wonder what if later.

BC.
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