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I'm in the process of looking for DOT cert. track tires for a set of Panamera 18" 10 spoke that I just picked up for the '88. I'm leaning in the direction of Toyo Proxes R888.
I gather that there's a consensus that the "safest" tire sizes of 235/40 for the front; and 265/35 for the rear will work well on all generations of 928's - at least the S4.
I'd also heard somewhere that if balance between front to rear circumferences of an aftermarket wheel set varies too much from that of stock, that it may disable the ABS. Is that true?
The circumferences of the 235/265 setup (“NEW”) will be close to that of the factory original S4 specs (“EXISTING”), and the front to back circumference variations are nearly identical to factory.
Front 235/40 comparison to stock:
Rear 265/35 comparison to stock:
The R888 are available in these sizes.
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But I'm considering going 10mm wider; front and rear and adjusting the aspect accordingly.
Front 245/40 comparison to stock:
Rear 275/35 comparison to stock:
The circumference difference between front and rear is nearly identical to the 235/265 combo, but but the speedo error is a bit higher. R888 are available in these sizes as well.
It looks as though the 245/275 combo. would work well with the 8"/9" wheels, if I were to go with the R888.
Anyone think otherwise?
I'd also heard somewhere that if balance between front to rear circumferences of an aftermarket wheel set varies too much from that of stock, that it may disable the ABS. Is that true?
Yes. When difference is above 5% it can cause problems for ABS, PSD and possibly even RDK.
Here's factory setups and some aftermarket sizes what work. I like to run 2-3% larger than stock diameter rubber so that speedo is dead accurate. Naturally wheel width determines how wide rubber can be. More hardcore driving wider wheel needs to be compared to tire width and narrower rubber needs to be compared to wheel width.
04-23-2016, 04:11 PM
