Found This information. It is for Caterham 7s, so perhaps its relavent to us.
Tyres Types For Sevens
There are a wide range of tyres commonly used on sevens. Wheel size should also be considered, larger wheels may look sexier but ride quality and handling both benefit from smaller wheels. 205/45R16 are therefore purely for looks, 195/55R15 are sometimes used as they are the smallest size that Potenzas can be found in - see below. 185/60R14 is perhaps the best size as it still has the same ground clearance as 15" and 16" due to its 60 profile. 13"/60 are best but give an inch or so less clearance, ACB10s and CR500s can only be found in this size. In rough order of descending dry grip:
Avon ACB10
These tyres are the same as used on Formula Ford race cars although there are 15 different compounds. The usual one for sevens, and indeed standard equipment on SLRs, is the A30 compound that gives about 3000 road miles on the rear and 2 or 3 times more on the front. An abrasive track session can wear them out in a day though. The are of rubber and glassfibre construction and so are exceptionally light, they do however require very different camber settings compared to normal tyres. They provide little grip in the wet and are very susceptible to aquaplaning. They cost around 100 quid a corner. More details at the Avon website .
Yokohama A032R
The 32 is the standard tyre for the discerning road sevener (When my 21s wear out I'm going to get some). They provide levels of grip approaching the ACB10 but are of conventional construction and so require no special set up but are much heavier. They also give similar levels of wear. They are rumoured to be a bit sharp on the limit compared to a 21R. They are around 75 quid a corner from George Polley Motorsport for 14"
Yokohama A038R
This was developed for the Lotus 340R Elise derivative. I believe it to be similar to a 32R in performance and it has a similar tread pattern.
Avon CR500
This was developed specifically for the Superlight R500. It is a conventional construction tyre that offers reasonable dry grip but reports from other sevens seem to suggest its wet grip is as good as a 21R in the dry. It has a tread pattern designed to shift water. Very expensive in the region of 125 quid. More details at the Avon website .
Yokohama A021R
The 21 has a conventional tread pattern but softer rubber than a normal tyre. This gives it much improved grip in the wet (unless very wet) and dry and 6000 miles per rear. They offer very progressive on the limit behaviour allowing a novice (me
) to hold huge slip angles with ease. George Polley do them for around 50 quid a corner. A very popular choice - I have them at the moment.
Bridgestone Potenza
This is an interesting case. Many championships only allow "List 1A" tyres as defined in the RAC blue book. This is to ensure only standard road tyres are used to keep costs down. However, the Potenza has a layer of softer rubber under the surface designed to ensure grip even on old tyres that have hardened somewhat. Thus many racers buy these and scuff them down to this soft layer. The problem is that they are only available in 15" so everybody had to buy new wheels to be competitive...
Michelin Pilot SX
Standard equipment on older Caterham dedion models. An unremarkable road tyre - my old ones are destined for the cavalier. 80 quid or so from any tyre dealer - don't do it, buy something from the list above
Avon ZZ1
The new standard equipment for all Caterhams (except SL/SLR/SLR500) this is very hard and is chosen to ensure that the scholarship race series drivers don't ever have to replace their types to keep costs down. Some people have apparently done two complete seasons of racing on the same set of tyres.
Michelin "Hard as rock"
Standard on Xflow Caterhams, most people give up trying to wear them out, 40,000 miles is nowhere near long enough...
Rob.
Ask for a 205 or 215 price 
