The question is: ALL else being equal, same track car with no changes made other than wheel size (same tire model at 205 width, even), which will turn a faster lap? 16x7 weighing 15 lbs with 205/45-16, or 15x7 weighing 11 lbs with 205/50-15, (both wheels with same offset)?
You would have to control for gearing of course, but I am pretty sure the 15 will be faster. It's not only the weight on the car but the energy to spin and slow down the weight.
Performance tire selection for the street, well, that's a different story.
In reply to aircooled:
The gearing would stay the same, they are both 23 inch tires...
It depends on the tire construction, the car, and the course.
On a rough course and light car, the higher sidewall flex of the 15" will probably be more beneficial and on a light car the weight difference will matter more.
On a heavy car and a smooth course, the presumably stiffer construction of the 16" tire would presumably be beneficial.
Also, keep in mind that true section widths can often vary, I'd venture to say that it's very likely the 205/45/16 would have a slightly larger contact patch than the 205/50/15.
I think both would lose to 225s on a 15x9. :)
drdisque wrote: It depends on the tire construction, the car, and the course. On a rough course and light car, the higher sidewall flex of the 15" will probably be more beneficial and on a light car the weight difference will matter more. On a heavy car and a smooth course, the presumably stiffer construction of the 16" tire would presumably be beneficial. Also, keep in mind that true section widths can often vary, I'd venture to say that it's very likely the 205/45/16 would have a slightly larger contact patch than the 205/50/15.
Good observations! In this case the car is FWD and will be right at 2400 lbs total with driver and 1/2 about 6 gallons of gas, and 120 WHP. Thinking about performance on a tight, highly technical track with a main straight length of only 1300 feet (Hallett)
In reply to codrus:
9s won't clear the front struts without hella fat spacers, and that gives a wonky scrub radius.
codrus wrote: I think both would lose to 225s on a 15x9. :)
Or even 225s on a 15x8.
But I think the 15x7s would be faster between those two, the difference in unsprung weight alone would do it.
In reply to GameboyRMH:
Hence why I'm a fan of 13x8's. They mess with your gearing a bit though. With the 4.3 FD and 13s my miata is a mess at certain tracks.
http://exomotive.com/store/traklite-13x8-launch-wheels/
I would think that, given the 16" setup would probably find best grip at lower slip angles, a car with less than ideal suspension geometry might prefer the 15s. Practically every car ever has imperfect geometry, not all four tires (or even both tires on a given axle) will be working optimally since one or the other will be working either with too much slip angle or not near its peak performance yet.
This is assuming that the 16s have a theoretical performance advantage to begin with. They may, they may not... tire manufacturers have been known to use different compounds or construction on different sizes.
You'll need to log in to post.
