Quote:
Originally Posted by RT-BRZ
Since my season is basically done for Solo, what are everyone's thoughts on tire size? I ran RT660's in 255/40/17 and I thought they were fine but as the season progressed I always felt like I was a little off from others in BRZ/FRS/86 cars. At first I just chalked it up to my skill level but I ran a Track Event at Mid-Ohio in September and the car was definitely slower than last year when I ran 245/40/17's and no tune or header or any of the significant STX prep I did.
So, I feel like the verdict is that the 255's are actually a detriment but I am wondering what everyone else has experienced or thinks.
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I've tried. I don't feel like it worked that well, here's my mental model for how they fare.
255s are a bonus on speed maintenance courses that also have a sustained high speed section at around 63mph. You're slightly faster than everyone on 245s there. So, like 10% of courses.
On pure speed maintenance courses (zero digs) with top speed <= 62mph (245s not bothered by the rev limiter) or with top speed > 64mph (everyone deep into third), there is no advantage either way. This is maybe 30-40% of courses.
If there is even one or two big digs (so all other courses), you get destroyed by everyone on 245s. Generally speaking our cars are thrust-limited coming out of digs, not traction-limited, and you are reducing thrust.
Bottom line is wider rubber should help in theory, but the gearing changes add a course dependency factor that is much larger than any extra grip you might get.