tyreing question

[Chef]

with all the palava going on in F1 with tyres, does anyone know if there are any restrictions on tyres for Le Mans. These are v quick cars and i was wondering if the motorsport fia wants to make le mans as safe as F1 is now with grooved tyres, ect?
Do they have a limited number they can use in the race? any set size?

[Rhino]

They do have set dimensions, but no restrictions on how many. It's all to do with how long you spend in the pit's. You can't change tyres while refuelling so it's best to make them last a few stints. Therefore the tyre compounds are harder.
I seem to remember in the early eighties you were only allowed 24 pitstops during the race, they would use 23 for fuel and tyres and one for emergencies. Of course i was young and didn't drink much then so could remember these trivial facts!

[DelBoy]

I think you are a bit wrong there, Rhino, regarding a limit on the number of stops.  The old C1 cars of that era (wish it was the same categories today!!!), just like the current lmp900 cars, used to refuel every 35-40 mins.  So that means a minimum of 36 stops.

The only limit I can remember was that each car was allowed only so much fuel for the whole race - I think it was 2500 litres for the C1 cars, and the fuel was metered at each pit.  This meant that the Porsches of the day could not use all their power with the twin turbos as they were too thirsty - they had to turn down the boost for some of the time.  It also meant that a partly wet race was somewhat interesting as they could conserve their fuel and still keep pace with the non-turbo cars, and step up the power during the dry periods.
The fuel flow during a pit stop was set at 1 litre per second, so a refuelling stop took at least 90 seconds.

Nothing to do with tyres, I know, but.....

DB

[Rhino]

The pitstop thing was before group C, i'm sure i remember reading about it somewhere.
What sort of out time did the older cars have? Could a Jag D stay out for a couple of hours?