Dunlop CR 65 pressure

[redcarandco]

Dear all of you "crazy" lotus elan race drivers I get a little bit old (71)and first time racing my old faithfull fitted with Dunlop 525 M 13 race tyres as we did in the sixties (we now only use avon cr6zz and modern road homologated tyres) but the rules of my racing serie begin to change and I really do not remember tyre pressure we used at this period .(1966).with Dunlop CR65..I do not ask you to reveal your secret I just would like to know where to begin to avoid time and tyres spilliage (not sure that's correct english)first trial done at 1.8bar and Dunlop gets dark blue at the exterior end of rolling face???Many thanks for all helps if it is not a state secret ...
Best regard Roger

[rgh0]

Hi Roger
I do not use historic racing tyres as my Elan racing class allows modern road legal high grip tyres which are clearly superior and much cheaper. My preference is Yokohama A-050R so i cannot give you direct data on your Dunlops but i am sure your local race tyre supplier can give you a starting point

However my approach when setting up a new tyres is to start at around 1.8 bar cold and then lower it slowly and see how the car reacts on the track in different conditions. Starting low and working up can ruin tyres and lead to interesting times in the middle of a race when the tyres overheat and go off. Starting high and working down is much more controllable

I have observed the outside edges of the front tyres of my Elan going blue over the years and I believe this is more due to problems with body roll and camber change in corners overloading the outer edge of the outside tyre. A reduction in body roll with stiffer springs and roll bar and increased negative camber within whats allowed by your class rules helps with this.

regards
Rohan

[Davidb]

When racing the Avon equivalent in the early eighties I contacted Tony Thompson and he (reluctantly) told me his pressures: 26 psi front and 24 psi rear. This seemed to work very well.