As I am about to get back on the road with my crossflow (hurrah) and its new Avon Academy tyres (it had 20+ year old concrete blocks on before!), I'm looking for some guidance on pressures.
The Caterham little green book says 20psi for 13" wheels. That was written a long time before the current academy tyres though.
The Avon guide says 32-36 hot on track.
My instinct said 18 cold. But even 20 cold is unlikely to get to 32+ on the road I feel. Any real world experience and advice out there please?
I went with 18 cold for road and track. I found the tyres to be predictable when you exceeded the limits of grip which made for enjoyable track driving.
I eventually replaced them with Uniroyal Rainexpert of the same size which perform about the same. Better in the rain, though comparison is not totally fair as the academy tyres I had were second hand from a racer so had had a very hard life.
1.6K Roadsport SV
Does the Avon guide refer to those tyres on a CAterham, or a tintop carrying much more weight. If a Caterham, i'm very surprised.
The Avon spec is specifically for Caterham Academy cars, it shows a 30PSI pressure for normal use:
I don't think that's a recommendation for use, just how the dimensions are measured. I'd be surprised if anyone runs them at that on a 7.
13" ZZRs are measured at 22, larger sizes 26-30 etc. No mention of them being recommended running pressures which will vary widely depending on vehicle
That table shows the pressure used when measuring the tyres rather than reccomending any value to use when driving.
1.6K Roadsport SV
As it is the only tyre of it's type in only the one size, then it would make sense that it is engineered to operate at 30PSI. On the road I would start at 28PSI and track 25PSI to aim for 30PSI at operating temperature. This is borne out by the fact that the 13" ZZS tyres are measured at 22PSI (for sizes that are typically Caterham specific) compared with higher pressures for most of the 15, 16 and 17" ones:
Other tyres on Caterhams may also need to be operated at non-intuitive pressures based on the design of the tyre, not purely on the car weight. The CR500s certainly seem to be happy at the 18PSI to 20PSI range, but I had been struggling with the right tyre pressure for the Nankang AR-1s when I switched to them.
Conventional wisdom dictates that you mark the tyres with chalk, measure the evenness of temperature across the tread and look for tread roll-over to the edge of the tread. Doing all this on the AR-1s indicated I needed a lower pressure. After I reached 14PSI cold (20PSI hot on track) and still experienced significant inner tread wear and little outer tread wear combined with less grip than expected, I upped the cold pressure to 21PSI (26PSI hot on track), which solved all the issues and reduced my lap times by over 2 seconds on a 90 second lap. Then I found the Nankang track pressure recommendations. They indicate for an 800kg or less car that the hot pressure should be in the 24 to 27.5PSI range, no lower if the car is proportionately lighter.
Good point, better wait for someone who knows what the Academy folks actually use.
1.6K Roadsport SV
Thanks all. The Avon document is linked on the old club url when you do a search. It's definitely talking about caterham motorsport and it says 32-36 hot for the academy tyre.
To get there in road driving you'd have to start pretty high I think 25-28. My instinct was to start at 18! But that's just a guess.
I'd start at 18psi.
Democratic dissent is not disloyalty, it is a positive civic duty
"The Avon document is linked on the old club url when you do a search. It's definitely talking about caterham motorsport and it says 32-36 hot for the academy tyre."
This from 2021?