Enkei RPF1 15x7 vs 949 6UL 15x8 for track??

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Enkei RPF1 15x7 vs 949 6UL 15x8 for track??

Post by dontblink »

I have a 96 Miata, dedicated track car used for HPDE and potentially NASA/SCCA TT. I use 205/50x15 G-force R1 tires and will be staying with that size.

My delimma: Enkei RPF1 15x7 wheels weighing only 9.8lbs or 949 6UL 15x8 weighing 12.3lbs.

The 15x8 will stretch out my 205 tires giving me added contact patch and stiffer sidewall. But I'm sacrificing unsprung weight compared to the lighter Enkeis.

It's hard to know whether the added power due to less unsprung weight is a bigger benefit or the added grip. I tend to think handling wins over hp, but when you've only got about 120hp at the wheels, maybe not.

Thoughts? Let's assume price isn't a factor.

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Re: Enkei RPF1 15x7 vs 949 6UL 15x8 for track??

Post by Brian »

It's an easy choice, assuming that 205/50/15 size.... the 15x8 will be faster. The few pounds per corner would make worse ride quality in the real world but for a race car is not enough weight to make much performance difference here. In contrast, for a few extra pounds the 15x8 has BIG advantage with significantly more stable contact patch, and more tire actually on the ground, etc. The better turn-in response will be more confidence inspiring, car will be easier to drive fast, etc.

Tire not stretched at all, sidewalls will be nice and square, that's an eight inch wide tire on an eight inch wide rim....which means tire will be happy and wear more evenly and perform more consistently throughout tire life, etc.
Brian Goodwin
Good-Win Racing
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