Tire Pressure for HPDE track event
05-21-2010, 09:36 AM
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I am going to the track on Monday for my first track event. What tire pressure should I run? 2006 BMW 550i sport with stock 18" runflats.
based on some reading I was think of starting at 32 psi cold. any thoughts?
based on some reading I was think of starting at 32 psi cold. any thoughts?
05-21-2010, 09:55 AM
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My Ride: 2005 545i
SPF Cobra #1019
For normal street driving, I set mine to what the manual states for 5 passengers + luggage ('05 545i with 18" M-PS2's = 36f/41r). I would suggest that you go 5lbs over whatever it states in your manual for 5 passengers + luggage.
Have fun!
Have fun!
05-21-2010, 11:33 AM
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My Ride: '06 550i
'84 Nissan S12 Turbo
Isn't it 36 rear, 33 front for "speeds over 100mph"? I think that's what it says on the label in the drivers side door frame. Anyway, I have a DE event coming up in a couple of weeks as well, and on my 550 with staggered 18" runflats I was thinking going 2-3 lbs over....so say 38-39 rear 34-35 front....and see how that feels and go from there
05-21-2010, 12:01 PM
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I'm getting ready to go to my first event this weekend. From the RMC BMW CCA Driving School Student Manual:
"For the performance driving you will be doing, you should inflate your tire to pressures above those normally used on
the highway. With higher pressures, the tires will be able to generate higher cornering forces and will not roll onto
their sidewalls during cornering. Recommended cold tire pressures are 38-40 psi in the front and 36-38 psi in the rear."
I'm not sure if there is any adjustment for altitude.
"For the performance driving you will be doing, you should inflate your tire to pressures above those normally used on
the highway. With higher pressures, the tires will be able to generate higher cornering forces and will not roll onto
their sidewalls during cornering. Recommended cold tire pressures are 38-40 psi in the front and 36-38 psi in the rear."
I'm not sure if there is any adjustment for altitude.
05-21-2010, 01:27 PM
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My Ride: 2008 550i Sport (6-speed)
I don't know about your experiences on the track but i tend to let the air out as the day goes on. The heat generated in my tires increases the tire pressure up to just over 12 psi. If you increase your tire pressure, along with the speeds you may be traveling + corners + braking you could go over the maximum tire pressure for the tire per the manufacturer's recommendations.
05-21-2010, 01:46 PM
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My Ride: 2008 BMW 550i
2006 BMW X3
I don't know about your experiences on the track but i tend to let the air out as the day goes on. The heat generated in my tires increases the tire pressure up to just over 12 psi. If you increase your tire pressure, along with the speeds you may be traveling + corners + braking you could go over the maximum tire pressure for the tire per the manufacturer's recommendations.
Also note how much tire squeal you get. If too much, the tires overheat and loose grip, causing more squeal. back off to where there's no squeal, and the tires will cool a bit, giving you some grip back, allowing faster corners without squeal.
05-21-2010, 03:18 PM
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My Ride: 2008 550i Sport (6-speed)
However, reducing the tire pressure causes the tires to roll over too easily, causing tire pressures to build quicker. The result is inconsistent grip. If you increase the pressures, they won't go up as much. I always start a few psi over what's indicated for max load and watch closely. Only if you get too close to the max shown on the sidewall, then decrease the starting point for the next run.
Also note how much tire squeal you get. If too much, the tires overheat and loose grip, causing more squeal. back off to where there's no squeal, and the tires will cool a bit, giving you some grip back, allowing faster corners without squeal.
Also note how much tire squeal you get. If too much, the tires overheat and loose grip, causing more squeal. back off to where there's no squeal, and the tires will cool a bit, giving you some grip back, allowing faster corners without squeal.
05-21-2010, 06:01 PM
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My Ride: 2007 550i Titanium Grey Metallic - 6 Speed Manual, Sport Suspension, Premium, Cold Weather, Navigation, Shades, L7 Sound
Here is a link on tire pressures. I thought this was helpful... was given to me today.
http://www.tirerack.....jsp?techid=147
http://www.tirerack.....jsp?techid=147
Check and Adjust First Thing In The Morning. Set according to the vehicle manufacturer's cold tire pressure(s) recommended on the vehicle's tire placard or in its owner's manual. This must be done before rising ambient temperatures, the sun's radiant heat or even driving short distances temporarily warms the tires.
Accommodating Variables
Indoor-to-outdoor Temperature Variation. Significant differences between the conditions tire pressures are set (the warmth of an attached garage, heated garage or service shop) and in which the vehicle will be driven (winter's subfreezing temperatures) requires inflating tires 1 psi higher than recommended on the placard for every 10° F difference in temperature between interior and exterior temperatures.
Afternoon Ambient Temperature Increase.* Set 2 psi above vehicle manufacturer's cold inflation recommendations when installing new tires or if the vehicle has been parked in the shade for a few hours.
Tire Heat Generated While Being Driven (or at speeds of less than 45 mph).* - Set 4 psi above vehicle manufacturer's cold inflation recommendations.
Heat Generated While Being Driven Extensively (or at sustained speeds greater than 45 mph).* Set 6 psi above vehicle manufacturer's cold inflation recommendations.
Do Not Release Hot Tire Pressure if any of these variables could be the cause of measured tire pressure exceeding the maximum psi branded on the tire's sidewall by the 2, 4 or 6 psi indicated above for the various conditions. This temporary pressure increase is expected and designed into the tire's capabilities.
*NOTE: Tires on a parked vehicle exposed to direct sunlight will appear overinflated due to the heat absorbed from the radiant energy of the sun. Pressures cannot be accurately set on these tires until all have stabilized in the shade.
Accommodating Variables
Indoor-to-outdoor Temperature Variation. Significant differences between the conditions tire pressures are set (the warmth of an attached garage, heated garage or service shop) and in which the vehicle will be driven (winter's subfreezing temperatures) requires inflating tires 1 psi higher than recommended on the placard for every 10° F difference in temperature between interior and exterior temperatures.
Afternoon Ambient Temperature Increase.* Set 2 psi above vehicle manufacturer's cold inflation recommendations when installing new tires or if the vehicle has been parked in the shade for a few hours.
Tire Heat Generated While Being Driven (or at speeds of less than 45 mph).* - Set 4 psi above vehicle manufacturer's cold inflation recommendations.
Heat Generated While Being Driven Extensively (or at sustained speeds greater than 45 mph).* Set 6 psi above vehicle manufacturer's cold inflation recommendations.
Do Not Release Hot Tire Pressure if any of these variables could be the cause of measured tire pressure exceeding the maximum psi branded on the tire's sidewall by the 2, 4 or 6 psi indicated above for the various conditions. This temporary pressure increase is expected and designed into the tire's capabilities.
*NOTE: Tires on a parked vehicle exposed to direct sunlight will appear overinflated due to the heat absorbed from the radiant energy of the sun. Pressures cannot be accurately set on these tires until all have stabilized in the shade.
05-21-2010, 06:08 PM
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I ran my 2004 545 at Texas World Speedway last weekend. I started with recommended pressures; however, using tire pen (you can use chalk) I realized that the tires rolled beyond the roll mark on the sidewall. Increasing pressure to 40 psi all around allowed the tire to roll just up to the tip of the roll mark. As "safetywork" stated above, check your pressures right before you go out, as a 25 minute session on a 2.9 mile course with 15 turns increased the pressure anywhere from 5 psi in the rears to 12 psi in the front passenger (running CCW).
05-22-2010, 10:00 AM
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My Ride: '07 530iSport PackageLuxury Packagemore to come
Back when I tracked my old car it was always recomended to run a couple of pounds pressure higher in the front than that back. That would help offset the built in understeer in BMWs. I saw that in one of the posts above and thought it was worth repeating. We also ran one side of the front higher than the other if the track had a lot more right hand turns than left. The higher pressure on the side that had the most use.