Tyre choice

21's, 32's, CR500's: which is best?

Somebody asked on the Sevens mailing list about the best road tyres. Here's my reply.

Chris Bradley wrote:
Thanks for all the ACB10 thoughts .... any ideas on CR500's vs. the Yokos?

I've currently got CR500s, but I have previously used 32s, 21s, and a variety of lesser tyres on my 7. I'm very impressed. They grip nearly as well as 32s in the dry, and in the wet they are at least as good as 21s (and both are far better than 32s).

In terms of wear the CR500s are looking like they are going to outlast the 21s by some margin. I got 6k miles rear / 12k miles front from 21s, and 3k miles rear / 6k miles front from 32s. Both of these include some trackday action. All the Yokos wore out the middle of the rears much more quickly than the outsides (despite only being 16 psi - I daren't go lower). The CR500s are wearing much more evenly, both across the tyres on the back, and in terms of front / rear balance.

One thing to watch with CR500s is that they very noticeably lower the car, which alters the suspension geometry. After putting them on the car felt great, but it wouldn't make it over a pebble without grounding. I've now got the ride height just about high enough, but the geometry isn't as good as when I first fitted the tyres (still very good though).

Regarding ride quality, all of these tyres are stiffer than ordinary tyres. 21s feel great on the road, and CR500s are similar. In my opinion, both are nicer than 32s which jar a bit too much. 32s are also noisier than the other two.

In defense of 32s, don't worry about them in the wet. I've run them through the winter, and they're nowhere near lethal, in fact they are still better than "ordinary" tyres on a 7. Just take it easy if there's standing water around.

One final thing. I don't know what kind of tyre you are coming from, but any of these are far better on a 7 than any "normal" road tyre. I've used Yoko A539s, A520s, A510s, Goodyear Eagles; what a waste of time. Pick any of the ones we've been mentioning and you'll see a huge improvement in the car.

Me, I'll be buying more CR500s when these have worn out.

Disclaimer: I have never used ACB10s because I can't afford it (I do about 12k miles /year) and I don't like what I've read about the handling characteristics (principally tramlining) for the road.

Postscript: I've now done 8,000 miles on the CR500's and the nearside rear is getting close to the legal limit. The fronts still have loads of tread. If I can make it to 9,000 miles then they will have lasted 3 times as long as 32's and 1.5 times as long as 21's (6k on the rear; 12k on the front). Considering also the performance and price, I think that makes them a bargain.

7^th July 2004: I had new rear CR500's fitted this morning, after 8,439 miles. The nearside tyre was [ahem] right on the limit, but there was some legal tread remaining on the offside tyre. Both fronts have plenty of life in them yet. I got the tyres direct from Avon and had them fitted, as usual, by Bracknell Tyres. Excellent services from both.

This page is http://www.strangely.org/diary/200406/tyres.html. It was first published on Friday 25 June, 2004 and last updated on Wednesday 7 July, 2004.