Historic racing tyres L or M section

[carreraplanes]

Anybody know what's the difference in terms of historic racing eligibility between Dunlop L section and M section 204 compound tyres? I've got a stack of M section tyres with my pre 66 Imp but some of the events I could be entering specify L section. What's the thinking here

[ChevronB19]

It’s all about dates to be honest, L sections were slightly ‘earlier’ than M sections.

I’ll tell you a secret that nobody agrees with other than my own tiny mind. I race in series which specify either L or M (depending on series). If it’s a series which allows M (and therefore L),and it’s wet, I use the L’s. I’m convinced, at least for my driving style, that L’s give slightly (and I mean slightly) more grip in the wet.

I take it you’re talking about HRSR? I know CTRCC are now allowing modern tyres, which to my mind ruins it, the fun is in the sliding on objectively ‘bad’ tyres. Rare for me to agree with s9meth7ng that is more expensive than the alternative.

They’re all too bloody expensive though!

[ChevronB19]

carreraplanes said:

Anybody know what's the difference in terms of historic racing eligibility between Dunlop L section and M section 204 compound tyres? I've got a stack of M section tyres with my pre 66 Imp but some of the events I could be entering specify L section. What's the thinking here

Oh, don’t forget that both L and M go *very* hard in sunlight or after stored for a bit, definitely keep them in bin liners if you have a few

[carreraplanes]

Thanks Chevron. I'm doing HRDC. Several classes based on year. The requirements for tyres on the entry forms read different every time but run something like:

DUNLOP ‘M’ SECTION CR65 ‘204’ - FIA CARS ONLY (or ‘L’ SECTION)

Not sure what it means FIA cars only as you don't need papers to run just need to be in period spec or so it seems. Or perhaps FIA cars are defined as post 64 only for some reason?

Did have the tyres stacked in a dark corner of the garage. Will put them in council bin bags, thanks for the advice. I did buy a durometer and they all came up about the same. Is there a target reading I should be looking for on the 204 compound

[ChevronB19]

carreraplanes said:

Thanks Chevron. I'm doing HRDC. Several classes based on year. The requirements for tyres on the entry forms read different every time but run something like:

DUNLOP ‘M’ SECTION CR65 ‘204’ - FIA CARS ONLY (or ‘L’ SECTION)

Not sure what it means FIA cars only as you don't need papers to run just need to be in period spec or so it seems. Or perhaps FIA cars are defined as post 64 only for some reason?

Did have the tyres stacked in a dark corner of the garage. Will put them in council bin bags, thanks for the advice. I did buy a durometer and they all came up about the same. Is there a target reading I should be looking for on the 204 compound

I did HRDC and it’s predecessor (Top Hat) for many years. I’d read the regs you quote as if it’s an FIA car it must have M’s, if it’s not an FIA car it can have M or L (but can equally see how you could interpret it as M’s are only allowed on FIA cars), but if in doubt ring Julius.

[carreraplanes]

Thanks Chevron I'll contact Julius....

[corporalsparrow]

carreraplanes said:

Thanks Chevron. I'm doing HRDC. Several classes based on year. The requirements for tyres on the entry forms read different every time but run something like:

DUNLOP ‘M’ SECTION CR65 ‘204’ - FIA CARS ONLY (or ‘L’ SECTION)

Not sure what it means FIA cars only as you don't need papers to run just need to be in period spec or so it seems. Or perhaps FIA cars are defined as post 64 only for some reason?

Did have the tyres stacked in a dark corner of the garage. Will put them in council bin bags, thanks for the advice. I did buy a durometer and they all came up about the same. Is there a target reading I should be looking for on the 204 compound

I’m in the All Stars and Coys. I’ve got Ms on my car, and I know Julius would rather I had Ls but he’s allowing it nevertheless. I’m half expecting him to have a chat at some point this year. If you’re in Touring Greats it’s really only Ls that are accepted and rightly so since the cars are predominantly 50s saloons.

It’s a great series, and you’ll love it.

[Keep it stiff]

I run on L's. I also have a used pair of M's. For testing purposes, could I get away with mixing and if so would I be better with the M's on the front or the back? It just pains me that I have the pair of M's doing nothing whilst I'm taking life out of the L's at £250 a shot!