WANTED - Trackday wheels

[jfgw]

Hi guys, I know it's a long shot, but I am looking for a used set of 13" rims for trackdays, so I can mount slicks. Also looking for used slicks if anyone has some left over. Preferred sizes 6" and 7".

Thanks
James

[jfgw]

Ok, so I was at the Vintage Racing weekend at Mid-Ohio this weekend and asked the onsite tire service what they did with their cast-offs...The basically said that they recycled them but if i wanted any, I could help myself! So long story short I got 6 on Fri (in an S2000) and another 6 yesterday. 10 are 7.0 x 20.0 x 13, two are 8.2 x 20 x 13.

I plan to use the 7 inch wide ones as they are closest to my current wheels/tires - 185/60 13 on 6" front and 205/60 13 on 7" rear, but here's the question..

the 7" avon slicks will fit on 6" to 8" wide wheels, so should i stick with 6 F, 7 R (i have to buy new wheels for them anyway), or should i go 7 F and R, or maybe 7 F and 8 R?

WOuld like to keep suspension etc the same.

Many thanks
James

[Ian7]

I have to say I'm a bit concerned that you are choosing wheels on the basis of whatever free tires you can find.
Please don't disregard issues like offset, wheel bearing loading, etc to save a few bucks on tires.
While I'm in 'nagging grandmother' mode, there's a reason those tires were in the recycle area. Most of us racers use our tires one session too many as it is .......

[jfgw]

Point taken Ian. I am certainly not planning to use the tyres to race with, and on a second set of wheels, if they are past a usable level, I can swap back to my road wheels and 48's on the track day. Having said that, they don't appear to be hard, and there is plenty of tread left, and they are in the size of tyre I would have chosen had I bought new.

The question was really based on the range of wheel rims that avon state the tyre will fit, and calling on the experience of other people who may have an opinion on which width would work best. Over on blatchat, people seem to be using anything from 6-7" on the front and 6-8.5" on the rear, using essentially the same chassis, hence my confusion!

[Kitcat]

Grssroot Motorsports recently reported that some of the advantage of a wide tire are offset if mounted on a narrow wheel. Apparently squeezing a wide tire on a relatively narrow wheel adversely affects the contact patch. This is only an issue where race rules mandate use of stock wheels. You can go as wide as you want since this is all for fun, so I think the lesson is don't go overly narrow on wheels.

Race tires can look great but have significantly limited grip if heat cycled out. Again, you are just doing this for fun so shaving that last second off your lap time isn't important.

Most races obsess over wheel weight and wheel/tire weight. The weight savings there are squared since those parts rotate. So a 4 lb savings per wheel translates to 16 lbs, times 4 wheels. It's also all unsprung weight which adversity affects handling as it goes up. All of that should be a consideration for you as well but again, since this is for fun, it is hardly worth mega buck wheels to gain a 1/2 second per lap advantage.

[TheDingo8MyBaby]

There are a couple of threads here..no idea if they're still available:

http://www.usa7s.com/vb/showthread.php?t=3350

http://www.usa7s.com/vb/showthread.php?t=2774

13x8 and 9 may be a bit aggrressive for you, but I love wide rims on the 7...especially with low offsets.

[Ian7]

Wider wheels and tires can look really cool, but if you change front offset too much, the corner weight jacking when the steering wheel is turned will work againsy any advantage you get from more rubber on the road, ditto caster effects will change the contact patch shape alarmingly.
Then there's the question of tire temps - - too big a tire will not heat up sufficiently with our lightweight cars. Its been shown numerous times that max grip is achieved with sensibly-sized, good quality tires....