Solo2 tire pressures, another approach.

[Guest turboman]

Read the latest SportsCar publication by the SCCA.There is an interesting article about slalom handling and balancing a car with tire pressures. In a stock class there's not that much you can do, beyond gaining more solo experience.

 

John Rastatter (quoted in the article) is Manager of the tire performance aspects of TireRack. He used to have a Goodrich dealership in Milwaukee in the '70's, and he ran a box stock Camaro with an automatic tranny. I don't think I ever saw him beat in his class, in a car that just shouldn't be winning. He was exceptionally smooth and a pleasure to watch.

 

Peter Cunningham, driver and owner of RealTime racing that runs an Acura in the National Pro road racing series and leads the points race also lived and soloed in Milwaukee in those days at the same events as Rastatter and myself.

 

Something we used to do to make a car 'dance" better was to run like 50 psi in the fronts and 48-52 in the rears, depending how the car balanced when tossed into a corner. With just the right combination a car car will slide and dance like a ballet ice skater. The higher pressures will reduce the footprint size and traction but it makes the car's reactions razor sharp. With higher pressures in the rear it gets "looser" and and a car that would normally understeer will dance the tail with the best of them.

 

Higher (50 psi) pressure in the front will quicken the steering response and reduce the steering effort. It will prevent scrubbing and feathering the outside edges of your front tires, just like negative camber will. On a Omni GLH turbo I used to run it was one of the first factory cars that came with 50 series tires and higher pressures turned it into a FTD car.

 

Like Rastatter says in the article there are times when you want one end to break loose to get the balance that feels good to you. There's more than one way to skin a cat...

[Xenonk]

yup, as rookies will learn that most of time, they keep overdriving the car, thus adding pressure.. eventually, as the driver skills get better, the driver will realize that the tires are not rolling over as much, so the tire pressures will drop.. well, that's the learn curve that I know of.. smart drivers will realize this matter soon or later.

 

Keefe

[omarco]

So, is it safe to run 50 psi on stock 215/45/17 tires?

[Guest turboman]

So, is it safe to run 50 psi on stock 215/45/17 tires?

 

No problem. The higher pressure puts far less load on a tire than running a slalom course. With the virtually non-existant sidewalls on low profile tires the tread almost wraps itself up the sidewall. This is why you can get by with 35-40 psi. The carcass is already plenty stiff. Stiffer than they ever were in years past.

 

Higher pressures are not just an excuse for a novices "over-driving' a corner. It is a valid tuning system for novice or pro in a "stock' class. It changes the footprint shape of the contact patch and alters the front-to-rear traction loading. Which way you want to alter it depends on your cars characteristics and how you want it to respond.