What tire pressure you run on stock BTO21s
- Thread starter waypoint
- Start date
waypoint
mod squad
Wow! 30 is a big drop. You don't feel any carcass flex?
Sorry carcass flex?
I just found I got much better stick at this pressure. Tire wear doesn't seem any worse for the lower pressure.
W
WARPTH
Guest
waypoint
mod squad
Maybe not the appropriate term but I mean when a tire deforms or rolls under excessive force or lack of air pressure necessary to keep its shape when cornering.
I know that a lot of guys running stickier, more agressive tires at the track run those lower pressures. I just wasn't sure, with high mfg recommended pressures, that these tires would be happy at 30/30. Good to know they're working we'll for you there. Thanks.
F
Fazed
Guest
I run stock pressures in summer and drop the front to 32 in winter. I leave the back end at stock because I like an exciting back end.
F
Fazed
Guest
Oh, I don't have the stock tyres any more and I was glad to see the back of them. I'm now running Michelin pilot road 3's and get much better feedback from the front now than I ever did with the Bridgestones. I got 9500kms out of the stock tyres, I probably could have pushed them for 1000kms more though.
I guess I should state the environment I'm in. The warmest air temp I'm ever really in is 35c (95f)at that is only for a month. On average I'm in air temps of 5 to 20 c (41f to 68f). Also I may not be as an aggressive rider so please take my recommendation with a grain of salt
W
WARPTH
Guest
the reason they run such low pressures at the track is because the tyre is under that much load constantly that it doesnt have a chance to cool. 30 psi in a slick or a super sticky road tyre quickly becomes 35-37 psi after a lap of hard cornering (depending on the compound). a trip to the canyons with your bridgestone will be lucky to see it rise 2-3 psi.
F
Fazed
Guest
Street
A technique for those wanting to get the most out of their tires on the STREET is to use the 10/20% rule.
First check the tire pressure when the tire is cold. Then take a 30-40 minute ride on your favorite twisty piece of road to get your tire temperature up, then measure the tire pressure immediately after stopping.
If the pressure has risen less than 10% on the front or less than 20% on the rear, the rider should remove air from the tire (to increase heating affect of carcass flex). So for example, starting at a front tire pressure of 32.5 psi should bring you up to 36 psi hot. Once you obtain this pressure increase for a given rider, bike, tire, road and road temperature combination, check the tire pressure again while cold and record it for future reference.
Each manufacturer is different. Each tire model is different.
A tire design that runs cooler needs to run a lower pressure (2-3 psi front) to get up to optimum temperature. Remember carcass flex to generate additional heat.
The rear tire runs hotter than the front tire on both road and track. So the rear tire cold-to-hot increase is greater.
Dropping air pressure has the additional side effect of scrubbing more rubber area, and can additionally add more traction at the cost of a little stability
As an example for 2004 Aprilia RSV Mille the recommended starting temperatures for STREET use are.
Front Tire 34.8 deg. Cold which in turn should be approximately 37.5 -38.5 deg Hot (3-4psi increase)
Rear Tire 39.4 deg Cold which in turn should be approximately 45-47 deg Hot (7-9psi increase)
Please note that these numbers tend to be too high for maximum traction but in turn increase the life of the tire.
A technique for those wanting to get the most out of their tires on the STREET is to use the 10/20% rule.
First check the tire pressure when the tire is cold. Then take a 30-40 minute ride on your favorite twisty piece of road to get your tire temperature up, then measure the tire pressure immediately after stopping.
If the pressure has risen less than 10% on the front or less than 20% on the rear, the rider should remove air from the tire (to increase heating affect of carcass flex). So for example, starting at a front tire pressure of 32.5 psi should bring you up to 36 psi hot. Once you obtain this pressure increase for a given rider, bike, tire, road and road temperature combination, check the tire pressure again while cold and record it for future reference.
Each manufacturer is different. Each tire model is different.
A tire design that runs cooler needs to run a lower pressure (2-3 psi front) to get up to optimum temperature. Remember carcass flex to generate additional heat.
The rear tire runs hotter than the front tire on both road and track. So the rear tire cold-to-hot increase is greater.
Dropping air pressure has the additional side effect of scrubbing more rubber area, and can additionally add more traction at the cost of a little stability
As an example for 2004 Aprilia RSV Mille the recommended starting temperatures for STREET use are.
Front Tire 34.8 deg. Cold which in turn should be approximately 37.5 -38.5 deg Hot (3-4psi increase)
Rear Tire 39.4 deg Cold which in turn should be approximately 45-47 deg Hot (7-9psi increase)
Please note that these numbers tend to be too high for maximum traction but in turn increase the life of the tire.
F
Fazed
Guest
Track
Track tire pressure is a different animal altogether. With track requirements the tire pressure is a +/- game which has a goal to getting to the proper temperature and pressure to maximize grip, feel, and stability.
Too much pressure leads to less contact patch and reduced grip
More pressure tends to give more stability (less rear wiggle)
Too much pressure leads to non-optimum tire Traction (but with tire wiggle)
Too little pressure leads to overstressed carcass and excessive heat (blueing of tire)
Too little or too much pressure leads to non-optimum tire temperature
For the track you'll have to drop the cold tire pressures an additional 10/20%. Track operation will get tires hotter (increasing the cold-to-hot pressure range) so starting at say 32/30 psi now should bring you up to the proper opreating temperature AND create enough tire pressure to maximize contact patch AND create enought feel and stability for the track. With these goals in mind the tire should be approximatly 35/36 psi when fully heated (at optimum tire temperature).
Since track riding put tremendous stresses on a "STREET" tire the tire heats up more than if it was on the street. "Race" tires will have different heat capabilities and are able to withstand the higher forces of a track better (ie cooler) than a street tire. The lower the tire pressure the more the tire deforms. The more the tire deforms, the more friction there is between the tire and the road surface. The more friction, the more heat. The more heat, the greater the opportunity the tire has to regenerate itself by shedding the 'used' layers of rubber (to a point). This deformation of the tire also creates a bigger contact patch at the cost of a little stability (ex rear wiggle).
Different riders have differerent starting pressures. You have two riders, 'super fast john', and 'average joe' go out on the recommended 31psi pressure and 'averages joe's' tires come in with the correct hot pressure (lets say 34-35 psi for example using Pirelli's reccommended hot pressure) you can bet that because that 'superfast John' will be working the tire harder, spinning it more and his tire might come in reading 37psi.
This would mean that to reach the target pressure of 34 psi which is the pressure and also temp that the tire works the best, 'superfast john' will need to take 3psi out of his tires and be starting at 28psi cold.
Track tire pressure is a different animal altogether. With track requirements the tire pressure is a +/- game which has a goal to getting to the proper temperature and pressure to maximize grip, feel, and stability.
Too much pressure leads to less contact patch and reduced grip
More pressure tends to give more stability (less rear wiggle)
Too much pressure leads to non-optimum tire Traction (but with tire wiggle)
Too little pressure leads to overstressed carcass and excessive heat (blueing of tire)
Too little or too much pressure leads to non-optimum tire temperature
For the track you'll have to drop the cold tire pressures an additional 10/20%. Track operation will get tires hotter (increasing the cold-to-hot pressure range) so starting at say 32/30 psi now should bring you up to the proper opreating temperature AND create enough tire pressure to maximize contact patch AND create enought feel and stability for the track. With these goals in mind the tire should be approximatly 35/36 psi when fully heated (at optimum tire temperature).
Since track riding put tremendous stresses on a "STREET" tire the tire heats up more than if it was on the street. "Race" tires will have different heat capabilities and are able to withstand the higher forces of a track better (ie cooler) than a street tire. The lower the tire pressure the more the tire deforms. The more the tire deforms, the more friction there is between the tire and the road surface. The more friction, the more heat. The more heat, the greater the opportunity the tire has to regenerate itself by shedding the 'used' layers of rubber (to a point). This deformation of the tire also creates a bigger contact patch at the cost of a little stability (ex rear wiggle).
Different riders have differerent starting pressures. You have two riders, 'super fast john', and 'average joe' go out on the recommended 31psi pressure and 'averages joe's' tires come in with the correct hot pressure (lets say 34-35 psi for example using Pirelli's reccommended hot pressure) you can bet that because that 'superfast John' will be working the tire harder, spinning it more and his tire might come in reading 37psi.
This would mean that to reach the target pressure of 34 psi which is the pressure and also temp that the tire works the best, 'superfast john' will need to take 3psi out of his tires and be starting at 28psi cold.
shadowman
New member
:rof::rof::rof:I think most guys on this forum like an " exciting back end "
C
Camo
Guest
I'm not sure what the done thing is but I run 32-34psi front, 38-40psi rear on the street and drop to 30-32 on track. They feel a little sloppy when you first hit the track but they feel firm about 3/4 of the way through first lap.... Sooner with these new S20's.
I was told to start at 30-30 on track and adjust to suit from there.
I was told to start at 30-30 on track and adjust to suit from there.
What you have to be careful of these days, if you run your bike on other than recommended stock pressures on the road, and you have an accident ( hopefully not), your insurance company could say you have not followed the terms of your policy, over here in the UK, you have to declare everything ( all mods ), not saying tyre pressures, but don't know if this applies in your neck of the woods.
I have heard of Insurance company,s refusing to pay out after an accident investigation., just my 
worth, so lets be careful out there everyone.
I have heard of Insurance company,s refusing to pay out after an accident investigation.
, just my worth, so lets be careful out there everyone.
W
WARPTH
Guest
What you have to be careful of these days, if you run your bike on other than recommended stock pressures on the road, and you have an accident ( hopefully not), your insurance company could say you have not followed the terms of your policy, over here in the UK, you have to declare everything ( all mods ), not saying tyre pressures, but don't know if this applies in your neck of the woods.
I have heard of Insurance company,s refusing to pay out after an accident investigation.
Ive heard of claims not being paid out here also due to tyre pressure
SeñorJack
El Guapo
i never have a problem with the stoc air pressure. are you properly warming up your tire? that is always my concern. i guess i do run 40 in the rear instead of 42, but only because its easier to read on my gauge haha
michelin PR3. they dont even need air they run on little whisps of the michelin mans soul...
michelin PR3. they dont even need air they run on little whisps of the michelin mans soul...