tyre pressures

garetgax · Post by **garetgax** » Wed Jun 17, 2009 8:04 pm

Given duncs comments re my fronts for the last round of the sprint being on the low side .what do you guys recomend i run the fronts at on Sunday? Any suggests guys?

Post by **Stuart** » Wed Jun 17, 2009 8:15 pm

Alan Meaker, Motorsport and Technical Manager of Toyo, talked to a few of us at length last night about the treble 8 for sprints. He was firmly of the opinion that for a typical event (around a minute of driving in the dry) that you could run as low as 18-20psi cold. This was based on a 1200-1250kg car

If you get the chance, why not PM Gerry and see if he can give you Alan's contact details.

Alan was of enormous help on Tuesday night and if he doesn't know the answers to your tyre questions you may be asking the wrong questions

duncan · Post by **duncan** » Thu Jun 18, 2009 6:42 am

I am sorry Stuart but I totally disagree with Alan on that.

Gerry H · Post by **Gerry H** » Thu Jun 18, 2009 7:04 am

duncan wrote:I am sorry Stuart but I totally disagree with Alan on that.

The dilemma Alan had on Tuesday, when making recommendations, was that the majority of cars were road first and track second with a max of 2.5deg. -ive camber.

Your application and experiences are quite different being ballsout for a tenth. We didn't have the ability to time so any adjustment benefits were only 'bum tested' Many of us had to drive home on the same tyres and same settings.

duncan · Post by **duncan** » Thu Jun 18, 2009 7:11 am

Still, in a sprint situation where you are running directly from cold I would certainly say that your pressures should be higher as the carcass will not have time to heat up as much and expand the air within.

If for example your cold pressure is 30 psi and hot pressure (after a track session) is 36 psi. I would start a sprint closer towards 36 psi.

It's not difficult to adjust pressures Gerry. :?

garetgax · Post by **garetgax** » Thu Jun 18, 2009 7:52 am

I was going to start with 34 psi and see what effect it had so by the sounds of it I wasnt too far off etc.

duncan · Post by **duncan** » Thu Jun 18, 2009 7:56 am

I'm not saying that those should be your target pressures Graham, but I think 34 wont be too far off the mark for a cold pressure.

Gerry H · Post by **Gerry H** » Thu Jun 18, 2009 8:03 am

duncan wrote:Still, in a sprint situation where you are running directly from cold I would certainly say that your pressures should be higher as the carcass will not have time to heat up as much and expand the air within.

If for example your cold pressure is 30 psi and hot pressure (after a track session) is 36 psi. I would start a sprint closer towards 36 psi.

It's not difficult to adjust pressures Gerry. :?

I'm ot an expert in five minutes but Alan's logic was quite er, logical

Sure tyre pressures are easily adjusted but with only 2 practice and 2 timed runs in an MSA sprint yoiu need to decide strategy quite quickly.

Horses for courses, as thy say. Come and do an MSA sprint Dunk

duncan · Post by **duncan** » Thu Jun 18, 2009 8:14 am

No thanks ...

tomcat · Post by **tomcat** » Thu Jun 18, 2009 8:53 am

Maybe I am getting confused here but for sprints surely you'd get better grip with lower pressures and they would warm up quicker with lower pressures -hence why heavy cars need more pressure and light cars need less pressure?