Lower tire pressures improve acceleration/ straight braking?

[g-force_addict]

Pretty much like dragster wrinkle wall tires do


Would these lower tire pressures also work in the front tires for straight line braking?
Assuming suspension geometry allows minimal or no camber change during diving to retain its full contact patch size?

[Jersey Tom]

Would these lower tire pressures also work in the front tires for straight line braking?

Ask yourself this first... when was the last time you saw an F1 car lock the wheels in straight line braking? There's so much downforce that you're limited by the size of the brakes - not longitudinal braking traction (at least that's my understanding for typical behavior).

[ubrben]

Montreal FP2, it was f***ing cold... But typically no...

Ben

[Holm86]

They help dragsters get grip by being elastic in the load direction. You definitely wouldn't want that when braking.

[olefud]

The wrinkle wall tires also provide an effectively smaller OD off the line with the tire OD growing with RPM and accompanying centrifugal force -a rudimentary CV transmission.

[riff_raff]

Actually, low tire inflation pressures might improve braking performance. The lower inflation pressures would increase the elasticity of the structural load path between the brake rotor and the tire contact patch, which would increase the margin between traction and sliding at the tire contact under braking. On the other hand, acceleration would be worse due to increased rolling losses in the tire.

[Tommy Cookers]

The wrinkle wall tires also provide an effectively smaller OD off the line with the tire OD growing with RPM and accompanying centrifugal force -a rudimentary CV transmission.

there has been a view that the tyre circumference is the same whatever the shape of the tyre (eg whether inflated or flat) ?
ie the revs/mile (hence 'gearing') is the same whatever the shape of the tyre

[Jersey Tom]

On the other hand, acceleration would be worse due to increased rolling losses in the tire.

I dunno about that. When you're talking about getting getting good power down and traction off the corner - how often is anyone talking about rolling resistance? Getting to throttle earlier is where it's at. (Whether or not "lower" inflation pressure gives that to you is debatable).

[Lycoming]

I only ever hear rolling resistance discussed when the available power is very, very, very small, ie. supermilage vehicles (3.5 hp), solar cars (2-3 hp) and streamlined bicycles (.5 hp).

The magnitude of the forces involved with rolling resistance are quite small when you have as much power as a dragster or F1 car.

[marcush.]

The wrinkle wall tires also provide an effectively smaller OD off the line with the tire OD growing with RPM and accompanying centrifugal force -a rudimentary CV transmission.

maybe not a different od but surely a reduced distance from hub centre to road ...as the Diameter of the wheel cannot really decrease the result is an elongated footprint..combined with shorter finaldrive?

[PhillipM]

I only ever hear rolling resistance discussed when the available power is very, very, very small, ie. supermilage vehicles (3.5 hp), solar cars (2-3 hp) and streamlined bicycles (.5 hp).

The magnitude of the forces involved with rolling resistance are quite small when you have as much power as a dragster or F1 car.

It's damned high for rally/dakar cars!

[theTTshark]

It depends on the tire, and the only way to see if it responds to lower pressures is to either stick it on a tire testing machine or do repeatable track testing. Do some tires like lower pressures? Yes. Do some tires like higher pressures? Yes. People will have examples of both.

[PhillipM]

The trend for F1 for quite some time has been to run them so low the manufacturers have had to try to stop them from doing it on some occasions...

[Luke]

The wrinkle wall tires also provide an effectively smaller OD off the line with the tire OD growing with RPM and accompanying centrifugal force -a rudimentary CV transmission.

there has been a view that the tyre circumference is the same whatever the shape of the tyre (eg whether inflated or flat) ?
ie the revs/mile (hence 'gearing') is the same whatever the shape of the tyre

unloaded maybe, but tyres don't stay round when vertical load is applied. the tread in contact with the ground flattens out and so the effective radius is reduced. The difference between the unloaded radius and the effective radius (which isn't the same as the loaded radius you can measure statically) is dependent on the tyre construction.

the tyre tread speed changes as it goes from the fastest at the top of the tyre (approx unloaded radius) to the slowest approx middle of contact patch. so actually neither top not bottom of the tyre is traveling at the same speed as the centre of the axle.

drag racing tyres on top fuel/doorslammer cars have hugely different effective radii from static to initial "hit" of the tyre to spinning at full speed.

[Pierce89]

But as TC said, the circumference doesn't change. Take a circle squash into an oval, the radius changes but the circumference doesn't. It's debatable whether a squashed actually effects gearing or not.