AWESOME! Most people who do that sort of testing wont share it. Kudos to you for your generosity!!!

Observations/questions:

Any camber wear in the old tires? Was it evenly worn across the tread?

The rolling diameter difference between the two is less than 3%, which isn't much advantage for the worn tires, but it is in their favor. The weight difference is less than half a percent, or less than the equivalent of 1/2 of a wheel hp on a course like that, if you prefer to think of it that way. Weight difference is less than 5% reduction in unsprung mass.

This all adds up to a pretty darn good test isolating the width difference (with tire age/tread depth.)

I agree with your assessment!

On such a fast, flowing course, the weight and particularly width advantages of the narrower wheel didn't necessarily get a chance to shine. I personally still think you'd get the same conclusion on a tighter course, but the margin would probably have been smaller.

If you do test the 15x9 next, I'd put in a vote to make sure you do it on a course that is tight enough to be representative of your most competitive venue (nats?).

 

Not too much camber wear because i turn/rotate them constantly

Nationals would be too far I might not be able to wait.

Just to pick your brain... what would you think would happen if I swapped tires and wheels, worn light tires on lighter wheels (around 25 lbs.)..???

thanks btw

Andres

 

dumb question, but what tire sizes were used on each wheel setup?

 

225-45-15

 

Thank you for posting your results, always to get more (any) data. I'd test 15x9 on all 4 corners next.

 

That will never happen , they don't fit the front unless you raise the car almost an inch.

Andres

 

A new opportunity is coming to try two equally worn (almost new) sets of RS3's one on 15x7 and the other one on 15x8 on a more curvy course.

Andres

 

we gotta find somebody in your area to kick in a pair of 15x9's for testing, too...

 

Cool Video... Sounds like you might need a new clutch or you were ridding the he'll out of it.

 

How much did you shave those tires?

Regarding the 15X9, I read here that all that was needed to fit them was 5mm spacers in the back and that's it. Can someone confirm or inform me better before I order my wheels?

 

Since all I have for good information is you guys, I ordered a set of 15X8 for my car to be on the safe side.

One of my friend has a Miata just ordered a set of 15X9 so I will be able to do some testing this summer.

I'll post what I find later on.

 

Its already been tested by spyderjuice, they fit fine if you aren't (Couldn't think another way to say this no offense intended) excessively lowered. 15x9 is noticably faster than 15x8s this has been known in the miata community for over a year now.

I suspect they didn't fit Andres' car because he doesn't have camber plates (correct me if I'm wrong) which move the strut shaft inwards giving more wheel clearance. Where exactly didn't the 15x9s fit your car Andres?