My SLO SHO LMS Tuned

[Signal13]

More area in contact with the ground so better traction/launches

Is that just track? How do they perform on hard corners and aggressive maneuvering?


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[Spyke]

Is that just track? How do they perform on hard corners and aggressive maneuvering?


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As far as I'm aware it's just for straight tracks, pretty sure it hinders any sort of maneuvering definitely not for courses or daily-ing

 

[bpd1151]

All correct info.

For gain in traction, mostly at the line, the lower psi is better.

However, then one must also factor in the rolling resistance.

Coefficient of drag increases with lower psi, so for road coursing etc., ideally more psi, rather than less.

 

[Signal13]

All correct info.

For gain in traction, mostly at the line, the lower psi is better.

However, then one must also factor in the rolling resistance.

Coefficient of drag increases with lower psi, so for road coursing etc., ideally more psi, rather than less.

This all actually makes sense now, thanks for the knowledge.


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[Livernois Motorsports]

DA plays a huge part in this as well as others said the tire pressure is too high, Forced induction cars tend to suffer extremely in hot and humid conditions especially if you drive the car to the track

 

[OmaHahn]

All correct info.

For gain in traction, mostly at the line, the lower psi is better.

However, then one must also factor in the rolling resistance.

Coefficient of drag increases with lower psi, so for road coursing etc., ideally more psi, rather than less.

I would love to know the exact science behind the tire pressure though - I understand the lower psi for traction and getting off the line, but what about once you get rolling? I always think about if I was riding a bicycle...with lower psi I'm struggling to pedal the bike and keep a fast pace - same true with a car?

 

[Lostneye]

I would love to know the exact science behind the tire pressure though - I understand the lower psi for traction and getting off the line, but what about once you get rolling? I always think about if I was riding a bicycle...with lower psi I'm struggling to pedal the bike and keep a fast pace - same true with a car?

Lower pressure allows the tire to deform more against whatever surface you are riding on, track, street, sand, snow, etc. Without the air pressure holding it up the tire flattens more against the surface and increases the contact area increasing traction. This is helpful at the staring line at the track or more for off road vehicles to not sink into sand or to form over rocks off road. Once up to speed the deformation creates for friction and higher rolling resistance creating drag like you would experience on your bike. The deformation and associated friction also can create excess heat at speed and cause premature failure if run like that for longer periods(remember the Firestone/Explorer tire recall?) When not drag racing the extra drag, heat, and squished sidewalls decrease gas mileage and make handling worse.

 

[brucelinc]

All good info. Another thing to keep in mind is the power of the car and the available traction at the track. A heavily modified SHO on a track that has not been prepped may certainly suffer traction problems and benefit from lower pressure to aid traction. On the other hand, a stock or tune-only SHO may not have traction issues at all and lower pressure would do more harm than good.

With my tune-only MKS, I always had my best runs at stock pressure. I would get just a hint of wheelspin at the line - enough to prevent the car from bogging but not enough to adversely impact forward motion. One of the tracks I run puts down sticky stuff at the starting line and I couldn't break traction there no matter how hard I tried. Even my RWD Mustang GT and other powerful RWD cars can leave the line with no wheelspin at that track.....as long as the attendants mop up any water that someone might drop.

 

[Lostneye]

All good info. Another thing to keep in mind is the power of the car and the available traction at the track. A heavily modified SHO on a track that has not been prepped may certainly suffer traction problems and benefit from lower pressure to aid traction. On the other hand, a stock or tune-only SHO may not have traction issues at all and lower pressure would do more harm than good.

With my tune-only MKS, I always had my best runs at stock pressure. I would get just a hint of wheelspin at the line - enough to prevent the car from bogging but not enough to adversely impact forward motion. One of the tracks I run puts down sticky stuff at the starting line and I couldn't break traction there no matter how hard I tried. Even my RWD Mustang GT and other powerful RWD cars can leave the line with no wheelspin at that track.....as long as the attendants mop up any water that someone might drop.

Good point, my fastest time(tune only) is at stock tire pressure but have had other runs where I had to drop pressure to hook.

 

[DON SVO]

Pulling air out of OEM or regular tired can actually hurt your track times. The sidewalls aren’t designed to reform like a good drag radial or a slick: so what ends up happening is that the tire can “cup” in the middle due to the stress from launch... this actually DECREASES contact patch and can cause more hazing (slight wheelspin) and worse times.

 

[SHOdded]

best tire pressure will depend on the tire being used, but many have netted best times at the drags by lowering pressures to as much as 25 psi (!). And some of the best times were set while running Eagle RS-As, which are not considered the best street tires by far.

 

[brucelinc]

For whatever reason, those RS-A Goodyears do seem to like lower pressures. They were kind of noisy stiffer riding tire and I suspect they have pretty stiff sidewall compared with Michelins.