The 24 Hours of Lemons Forums → Lemons Tech → tyre pressures
Im having a friendly battle with my team captain on what tyre pressures to run with on our 14" 195/50 Falkens.......I'd prefer to keep them a little softer at 25-28psi....he's in the 35psi camp?
Any preference from you fellows?
We run Falken Azenis as well and we start at 28 PSI cold. The trick is to not exceed 40 PSI when they get hot. It you start at 35 PSI you'll exceed that 40 PSI number and they will get greasy quick.
Sounds about right, thanks......
If you can, autocross your car and adjust your tire pressures accordingly. I start out at the max pressure (with the tires hot) and work my way down until they handle well. On my Mustang I run 51 (max) front, 48 rear.
Cheers Eric, seems high but my knowledge is all UK forest rallies and some short tarmac stages!
I think we'll go with the 28psi cold and see where she stands after the first hour or so........or is that being optomistic!!!
We run 28 psi cold, and never had a problem with the Azenis. Although we have not tried the new model of Azenis tire yet.
Roger!
We started our Direzza's at 32 cold and they came off right at 40 ... that's on a +/- 2900lb car.
The new 615K will hold up at 44PSI hot.
28-32 cold.
KT
Im having a friendly battle with my team captain on what tyre pressures to run with on our 14" 195/50 Falkens.......I'd prefer to keep them a little softer at 25-28psi....he's in the 35psi camp?
Any preference from you fellows?
Tire pressures? your car should tell you , not someone else..
Since we're talking about street rubber the tires don't get as hot as racing rubber does..
So we can use our hands to test tire pressure,
What? Yeh!
Use your hands..
When the car first comes in all hot from the track lay your bare hand on the tire.. Double check to make sure the tread isn't too hot but I've never found a street tire so hot I can't lay my hand on them long enough to feel what the tread is doing..
If the edges are hotter than the center increase tire pressure..
If the center is hotter decrease tire pressure..
If the outside edge is too hot add camber
If the inside is too hot decrease camber..
It's really pretty simple and doesn't require a lot of equipment..
If you can, autocross your car and adjust your tire pressures accordingly. I start out at the max pressure (with the tires hot) and work my way down until they handle well. On my Mustang I run 51 (max) front, 48 rear.
Actaully autocrossing requires differant tire pressures than road racing does.
and tire pressures should and do change from track to track..
Use your hands to test!
Can't with racing rubber but street rubber doesn't get hot enough (in my experiance) that I can't lay my hand on the tread and feel what's happening..
If the outside edges are hottest increase tire pressures,,
if the center is hottest decrease pressure
If the outside edge is hot increase camber,
If the inside is hottest decrease camber.
Keep record of what tire pressures and camber settings and you'll arrive at the track properly set up with one less thing to deal with..
Or buy yourself a pyrometer. But I've found that tire pressure is the absolute least of your worries at a Lemons race. If your car is in the paddock, you're generally changing a head gasket or fixing an equally catastrophic failure, not checking your tire pressure.
Besides, this is an endurance race. The extra 0.1s at the bleeding edge that perfectly set up pressures get you is worthless. If you're driving the car that hard, you're going to break something. Start at 30ish psi and forget about it.
Or buy yourself a pyrometer. But I've found that tire pressure is the absolute least of your worries at a Lemons race. If your car is in the paddock, you're generally changing a head gasket or fixing an equally catastrophic failure, not checking your tire pressure.
Besides, this is an endurance race. The extra 0.1s at the bleeding edge that perfectly set up pressures get you is worthless. If you're driving the car that hard, you're going to break something. Start at 30ish psi and forget about it.
I have to strongly disagree..
First from a practical standpoint.. tires setup correctly wear out more uniformly and will last longer.
Second from a safety stand point a car with the correct alignment for the race track will allow greater manuverability to avoid accidents/incidents.. Fewer black flags for off track excursions.
Third Comfort*/confidense.. lap times become consistant only with confidense and comfort in knowing the car and being able to predict what will happen in extreme situations..
If you keep track, you'll know that your car wants 28 pounds cold front and 32 rear with 3 thickand one thin shim for camber.. then when you go to that track that's what the car will have.. The next track might like 30 & 33 plus 5 thick shims.
* nope! we aren't talking arm chairs and slippers here!
If you can change an engine you can do an alignement using nothing more than some string.. Some pretty fast race cars have been aligned using nothing more than string including every single car I've raced and one that lead the Indy 500 (nope not mine, the guy who showed me how it's done) It's also been done recently in the pits during the race at NASCAR events..
Please ask, I'll talk you through the process.. Once you know what you are doing you can change alignment in about the time it takes to change tires.. (well maybe not as fast as NASCAR teams can change tires:)=)
Yes I own not only a pyrometer but also a digital lazer temp guage that I focus on a spot for about 2 seconds and it tells me the actual temps. Cost me I think about $50.00 and is wonderful for finding missfiring cylinders, brake temps and dozens of other things.
However for street tires, hands will tell you all you need to know
The 24 Hours of Lemons Forums → Lemons Tech → tyre pressures