Tire pressure....wait till you see what I run!

MonkeyButtRides

MonkeyButtRides

Registered
Ok this is probably going to get me blasted but I didn't see any recent discussions and I think it's always good to rehash tire discussions, bikes evolve, tires evolve, I'm getting older and fatter....

When I think back to a few years of amateur racing I did (twenty years ago...in a galaxy far away) tires had a max of 32psi but on slower, shorter tracks I would run (if memory serves me correct) as low as 26/27 psi. Less air gives you a larger contact patch but that also results in more friction which results in more heat so at higher speed tracks we would run closer to max psi. I don't race anymore, and it was a long time ago so my memory could be off but now days these hypersport tires q3+, s22's, etc...have a max psi of 42 which is insane to me but bikes now days are heavier and faster so I guess it makes sense.

For me when I'm local and doing more "sporty" rides I run around 30psi in my ZX10 and 34 in my Busa (it's heavier). Only time I run max (42) is when I'm on a road trip doing lots of miles and spending tons of time on top of the tire I want to maximize MPG's and wear, plus I'm carrying more weight with luggage.

So what do you all run in your bikes, not just your Busa's? I saw a link to an MC Garage video on tire pressure I thought was very good.
 
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Oh nooooooooooooooooooooo
1A1B9594-FABB-4214-80AC-8048CA8415F6.jpeg
 
MonkeyButtRides said:
Ok this is probably going to get me blasted but I didn't see any recent discussions and I think it's always good to rehash tire discussions, bikes evolve, tires evolve, I'm getting older and fatter....

When I think back to a few years of amateur racing I did (twenty years ago...in a galaxy far away) tires had a max of 32psi but on slower, shorter tracks I would run (if memory serves me correct) as low as 26/27 psi. Less air gives you a larger contact patch but that also results in more friction which results in more heat so at higher speed tracks we would run closer to max psi. I don't race anymore, and it was a long time ago so my memory could be off but now days these hypersport tires q3+, s22's, etc...have a max psi of 42 which is insane to me but bikes now days are heavier and faster so I guess it makes sense.

For me when I'm local and doing more "sporty" rides I run around 30psi in my ZX10 and 34 in my Busa (it's heavier). Only time I run max (42) is when I'm on a road trip doing lots of miles and spending tons of time on top of the tire I want to maximize MPG's and wear, plus I'm carrying more weight with luggage.

So what do you all run in your bikes, not just your Busa's? I saw a link to an MC Garage video on tire pressure I thought was very good.
Click to expand...
Lots of theories on contact patch and temps, if you are using a pyrometer to measure your carcass temps and tire warmers to preheat the tire no need to run low psi. Two ways to create heat in a tire, deformation and friction. So a low psi starting point gives much more deformation to the tire which is fine if you ain't running warmers. But if you have warmers and already can get the tire to temp it's best to not run such low psi. Your pace will dictate how much heat you can keep on a tire and that is in direct relation to your PSI. So if you start cold 28 and end up hot 36 you might as well go 34 to 36 hot. Live monitoring of tire pressures will always tell you if you are not keeping pace to your set PSI. If you run say 36 hot but while in track you drop down to 35 or 34 you ain't going fast enough to keep heat in the tire and should drop your hot PSI. When you have it dialed just right your hot and on track PSI should be the same or just 1 point higher never lower. Any adjustments after that are to match tire age, heat cycling, and how greasy the tire is getting. Too greasy a tire requires a drop in PSI. Smaller contact patches build up friction heat faster. That where a pyrometer or thermal map gun comes handy by adjusting PSI to actual temp of the tire. Each tire having a optimal grip range to temp ratio. In the end it's never about the size of the contact patch but of the temperature the contact patch is generating.
 
I believe it has a lot to do with the type of tire you use. If the tires are more track oriented, they probably have stiffer sidewalls that will make lower tire pressure quite tolerable. I have used Pirelli and Metzler racing slicks on the street in the last few years and I found less than 25 psi front and rear to be just fine. I stuck with 25 psi because any lower, I would fear damaging a rim on a bump.

SLICKS FOR STREET TIRES? | Tires

MonkeyButtRides said:
Ok this is probably going to get me blasted
Click to expand...
Fear not, all blasting is now focussed right on me!:fire:
 
I'm also frustrated by not being able to find a refillable air can / cartridge. You can find CO2 cartridge inflators as cheap as something like this Wayside CO2 Thread On Inflator, but I didn't know that CO2 leaks out of your tire and the next day it will need air again.
It turns out that CO2 is actually soluble in butyl rubber—it essentially melts right through the material without having to wait for permeation... Does CO2 leak out of tires? — Exploring Overland
Click to expand...
I'd like to take the freeway to the twisties, let some air out of the tire (maybe down to 32 to 34 hot), then be able to easily bump the pressure back up for freeway and regular riding (37psi) so I don't feel like I'm flat spotting the tire on the way home. Why the hell doesn't someone sell a portable canister with a valve on it that you could refill with air? Your typical gas station air compressor tank only puts out what? 100 PSI? Plenty! Even better, my local Costco lets you refill your tires with nitrogen pumps. It's frustrating. Right now I'm thinking about just bringing along my tiny light bicycle pump. But I would much rather have a small handheld cartridge inflator, even if it were the size of a insulated drink cup.
 
dcnblues said:
I'm also frustrated by not being able to find a refillable air can / cartridge. You can find CO2 cartridge inflators as cheap as something like this Wayside CO2 Thread On Inflator, but I didn't know that CO2 leaks out of your tire and the next day it will need air again.

I'd like to take the freeway to the twisties, let some air out of the tire (maybe down to 32 to 34 hot), then be able to easily bump the pressure back up for freeway and regular riding (37psi) so I don't feel like I'm flat spotting the tire on the way home. Why the hell doesn't someone sell a portable canister with a valve on it that you could refill with air? Your typical gas station air compressor tank only puts out what? 100 PSI? Plenty! Even better, my local Costco lets you refill your tires with nitrogen pumps. It's frustrating. Right now I'm thinking about just bringing along my tiny light bicycle pump. But I would much rather have a small handheld cartridge inflator, even if it were the size of a insulated drink cup.
Click to expand...

I have a small air compressor that plugs into the battery-tender pigtail for this reason.
It's in case of flat tires that can be plugged too.
I've never had to plug a sportbike tire on the road side(have had 2 tires blow out though, lol), but like to know that I can if I need to.
 
sixpack577 said:
I have a small air compressor that plugs into the battery-tender pigtail for this reason.
It's in case of flat tires that can be plugged too.
I've never had to plug a sportbike tire on the road side(have had 2 tires blow out though, lol), but like to know that I can if I need to.
Click to expand...
Same here, and yes it is very nice to know...
 
I listened to Fabio’s crew chief explain the problem they’re having with front tire pressure. He said they have to have covers for the front rotors not only for a small aero advantage but mostly to keep their rotors warm. Problem is, that the rotors get hot which transfers to a hot wheel which transfers to the tire making it increase in pressure throughout the race.
 
dcnblues said:
I'm also frustrated by not being able to find a refillable air can / cartridge. You can find CO2 cartridge inflators as cheap as something like this Wayside CO2 Thread On Inflator, but I didn't know that CO2 leaks out of your tire and the next day it will need air again. I'd like to take the freeway to the twisties, let some air out of the tire (maybe down to 32 to 34 hot), then be able to easily bump the pressure back up for freeway and regular riding (37psi) so I don't feel like I'm flat spotting the tire on the way home. Why the hell doesn't someone sell a portable canister with a valve on it that you could refill with air? Your typical gas station air compressor tank only puts out what? 100 PSI? Plenty! Even better, my local Costco lets you refill your tires with nitrogen pumps. It's frustrating. Right now I'm thinking about just bringing along my tiny light bicycle pump. But I would much rather have a small handheld cartridge inflator, even if it were the size of a insulated drink cup.
Click to expand...
I carry a battery powered inflator/ battery booster. Throw it in the backpack and good to go.
 
dcnblues said:
I'd like to take the freeway to the twisties, let some air out of the tire (maybe down to 32 to 34 hot), then be able to easily bump the pressure back up for freeway and regular riding (37psi) so I don't feel like I'm flat spotting the tire on the way home.
Click to expand...
I used to do that. The twisties were thirty miles away. The best I could do was to lower the tire pressure when I got there and just ride back on low pressure. The center did wear more than the sides but unless you're an exceptionally talented rider, that's going to happen no matter what you do. On your way back from the twisties, hit some freeway ramps, you'll feel a lot better about your tire wear.

I found that using a 200/55 compensates a lot for center wear on a rear tire. The more elliptical profile wears down more to a circle rather than a flat spot.
 
Mythos said:
I used to do that. The twisties were thirty miles away. The best I could do was to lower the tire pressure when I got there and just ride back on low pressure. The center did wear more than the sides but unless you're an exceptionally talented rider, that's going to happen no matter what you do. On your way back from the twisties, hit some freeway ramps, you'll feel a lot better about your tire wear.

I found that using a 200/55 compensates a lot for center wear on a rear tire. The more elliptical profile wears down more to a circle rather than a flat spot.
Click to expand...
I agree, the 55 profile tires don't square off as fast due to the high profile and angle of the tires. Dave Moss did a lot of comparison videos on tires with the same sidewall height. Massive difference in the overall arch of the tire even in the same sidewall sizing from brand to brand.
 
ZeePopo said:
How does a 240 tire behave with lower pressures?
Click to expand...
I ran it down to 30lbs to check the difference and to be honest did not feel much vs the 42. This bike is a highway cruiser for me so I figure no matter the PSI the tire will always wear funny.
Hayabusa Wannabe said:
29 PSI: 148 foot turning radius
42 PSI: 148 foot turning radius

Hrm, similar behavior.
Click to expand...
Ha! Yeah the 240 changes things a bit with the stretch but it isnt as terrible as some people say. When you need to turn, I have a second bike! LOL
 
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