Tyre pressure - Track day
06-02-2014, 04:21 PM
#1
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Tyre pressure - Track day
Hi guys,
next sunday i'll have my first track day!
My car is stock, with 225/50-16 front and 245/45-16 rear, street tyres...
The specified pressure for normal cruise is 2.5 bar, front and rear; at which pressure do you suggest me to inflate for track?
next sunday i'll have my first track day!
My car is stock, with 225/50-16 front and 245/45-16 rear, street tyres...
The specified pressure for normal cruise is 2.5 bar, front and rear; at which pressure do you suggest me to inflate for track?
06-02-2014, 05:57 PM
#2
Pro
Congrats! And get ready to get addicted!
As far as tire pressures, it's anyone's guess. If it's going to be cool out, and the track is relatively cool, you should probably start with standard pressures and adjust from there. If it's a hot day with a hot track, start out a little lower than 2.5 bar. If anyone at the track has a tire temperature gauge, that would be the best way to tell if any of your tire pressures should go down or up. You should take three readings across each tire as soon as you finish each session - inside, center, and outside. The inside should be hottest, the middle should be slightly lower than the inside, and the outside should be lowest. The total temperature difference between the inside and outside on those tires should be around 5 degrees Celsius. If the inside and outside temperature is the same, or if the outside temperature is higher than the inside, you probably don't have enough camber in the suspension, but for your first track day in a stock car, I wouldn't worry too much about the alignment as long as it's working well for the street.
For each tire, the way to tell if the pressure is too low or too high is by comparing the middle temperature with the outside temperatures. If the middle is lower than or equal to the outside, you need a little more pressure. If the middle is closer to or equal to the inside temperature, you need a little less pressure.
More importantly - have you flushed the brake fluid and filled it with new high temperature brake fluid, and also, do you have high performance brake pads? You don't need race track pads, but at a minimum you need stock Porsche pads and ideally you want to run a track day pad like Pagid Orange. If you haven't taken care of the brake fluid, you're almost certain to overheat the original fluid and have problems.
Also, you want to run a higher viscosity oil for the track day - a 15W-50 if you can find it. If you can't change the oil by then, you should short shift (keep the RPM's lower, try not to go over 5,000 RPM's) and make sure the oil pressure gauge isn't dropping low in the corners.
Good luck! Hope you have a great day!!
As far as tire pressures, it's anyone's guess. If it's going to be cool out, and the track is relatively cool, you should probably start with standard pressures and adjust from there. If it's a hot day with a hot track, start out a little lower than 2.5 bar. If anyone at the track has a tire temperature gauge, that would be the best way to tell if any of your tire pressures should go down or up. You should take three readings across each tire as soon as you finish each session - inside, center, and outside. The inside should be hottest, the middle should be slightly lower than the inside, and the outside should be lowest. The total temperature difference between the inside and outside on those tires should be around 5 degrees Celsius. If the inside and outside temperature is the same, or if the outside temperature is higher than the inside, you probably don't have enough camber in the suspension, but for your first track day in a stock car, I wouldn't worry too much about the alignment as long as it's working well for the street.
For each tire, the way to tell if the pressure is too low or too high is by comparing the middle temperature with the outside temperatures. If the middle is lower than or equal to the outside, you need a little more pressure. If the middle is closer to or equal to the inside temperature, you need a little less pressure.
More importantly - have you flushed the brake fluid and filled it with new high temperature brake fluid, and also, do you have high performance brake pads? You don't need race track pads, but at a minimum you need stock Porsche pads and ideally you want to run a track day pad like Pagid Orange. If you haven't taken care of the brake fluid, you're almost certain to overheat the original fluid and have problems.
Also, you want to run a higher viscosity oil for the track day - a 15W-50 if you can find it. If you can't change the oil by then, you should short shift (keep the RPM's lower, try not to go over 5,000 RPM's) and make sure the oil pressure gauge isn't dropping low in the corners.
Good luck! Hope you have a great day!!
06-03-2014, 10:03 AM
#4
Rennlist Member
A Formula R tyre is designed for track work & should be operated within its recommended pressure range & adjusted to maintain a constant temp across the tread as advised above.
A road tyre is not designed for the track - not the rubber compound, side-wall construction, tread pattern, tread depth or carcase construction.
I was advised by a Pro racing driver that non Formula R tyres needed to be inflated well above road pressures (36 - 44 psi cold) to withstand the rigours of the track, otherwise the sidewall distortion under load (I'm assuming you're driving hard enough to have the car four-drifting at speed) will result in a diminished contact patch in terms of size & shape, reduced control, excesssive shoulder wear & increased risk of separation from the rim.
A road tyre is not designed for the track - not the rubber compound, side-wall construction, tread pattern, tread depth or carcase construction.
I was advised by a Pro racing driver that non Formula R tyres needed to be inflated well above road pressures (36 - 44 psi cold) to withstand the rigours of the track, otherwise the sidewall distortion under load (I'm assuming you're driving hard enough to have the car four-drifting at speed) will result in a diminished contact patch in terms of size & shape, reduced control, excesssive shoulder wear & increased risk of separation from the rim.
06-03-2014, 02:02 PM
#6
Rennlist Member
A Formula R tyre is designed for track work & should be operated within its recommended pressure range & adjusted to maintain a constant temp across the tread as advised above.
A road tyre is not designed for the track - not the rubber compound, side-wall construction, tread pattern, tread depth or carcase construction.
I was advised by a Pro racing driver that non Formula R tyres needed to be inflated well above road pressures (36 - 44 psi cold) to withstand the rigours of the track, otherwise the sidewall distortion under load (I'm assuming you're driving hard enough to have the car four-drifting at speed) will result in a diminished contact patch in terms of size & shape, reduced control, excesssive shoulder wear & increased risk of separation from the rim.
A road tyre is not designed for the track - not the rubber compound, side-wall construction, tread pattern, tread depth or carcase construction.
I was advised by a Pro racing driver that non Formula R tyres needed to be inflated well above road pressures (36 - 44 psi cold) to withstand the rigours of the track, otherwise the sidewall distortion under load (I'm assuming you're driving hard enough to have the car four-drifting at speed) will result in a diminished contact patch in terms of size & shape, reduced control, excesssive shoulder wear & increased risk of separation from the rim.