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post #1 of 10 (permalink) Old 07-08-2002, 02:18 PM Thread Starter
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tire pressure

Folks,

For those of you experiencef riders and racers off and on track. What pressure do you set your tires for? I've heard several things, but I'd like to know what you guys recommend. I have a 98 7R and the recommended settings from the factory is 34/42?
I understand that the lower the pressure, the better the grip, but more wear and tear. The temperatures range in the 80's and is usually is dry. I have the So. Cal. mountains as a backdrop so keep that in mind.

Thanks.
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post #2 of 10 (permalink) Old 07-08-2002, 02:37 PM
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30/30 for anything but highway droning.

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post #3 of 10 (permalink) Old 07-09-2002, 05:50 AM
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31-32 F 34-36R

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post #4 of 10 (permalink) Old 07-15-2002, 09:32 AM
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rode Saturday with 33F 33R. Handled great through the twisties.

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post #5 of 10 (permalink) Old 07-15-2002, 10:47 AM
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You guys must rip thru tires? I do as much touring-type riding as hard twisty riding so I keep it just a couple pounds under spec.

It turned out the kangaroo was right.
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post #6 of 10 (permalink) Old 02-19-2003, 01:47 PM
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I have 30-33 fron and 33-36 rear.

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post #7 of 10 (permalink) Old 02-19-2003, 02:15 PM
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Quote:
Originally posted by Bonk!
You guys must rip thru tires? I do as much touring-type riding as hard twisty riding so I keep it just a couple pounds under spec.
I'm with you. I generally keep mine just under the max recommended and never had a problem. Didn't change the tires on our F4 until about 11,000 miles, and they were still usable. Neither of us is dragging knees through twisties though, and a lot of it was commuting. I never had a problem with grip though at those pressures when I did hit the twistie stuff.

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post #8 of 10 (permalink) Old 02-20-2003, 03:47 AM
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Actually since I originally posted this I have gone up to 36 front and 38 rear on my pilot sports.
Handling is lighter now and i prefer it that way.

There are some things nobody needs in this world, and a bright red, hunchback, warp-speed 900cc café racer is one of them -- but I want one anyway, and on some days I actually believe I need one. That is why they are dangerous.
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post #9 of 10 (permalink) Old 02-20-2003, 06:18 AM
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If you're not sliding, I wouldn't drop them, but if you are, 3-4 psi makes a BIG difference. For hard twisty riding on the street, that's what I do. Sliding is dramatically reduced. This is on an older heavy bike that recommends 36/42. On some of the lighter bikes, the recommendeds are lower. I know a lot of guys who use 32/32 on the street. I don't think I would ever go less than 30 at either end.

A tire gauge is standard equipment on my bike and is used often. Always know what your cold starting point was so that when warm, you can take a reading and then add or subtract the change that you're looking for. If in the course of the ride, you will then have an interstate blast of 50+ miles on the return, stop and inflate back to recommended cold pressure by getting the hot reading, doing the arithmetic, and adding the difference.

I run recommended for normal driving, drop 3-4 for spirited street riding, add 2-3 for continuous interstate, and have gone as low as 30/30 on the track which is 12 out of the rear and 6 out of the front. The hardest riding you can do on the street just doesn't compare to the torture they get on the track. That torture results in heat, which results in higher pressure, that actually puts the tire back to something similar to the recommended pressures. Hope that helps.

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Last edited by Dad; 02-20-2003 at 06:23 AM.
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post #10 of 10 (permalink) Old 02-21-2003, 03:31 AM
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Determining Best Tire Pressures

You'll get a lot of opinions on what tire pressure to run, but the correct tire pressure for you is not a matter of polling other rider's opinion. Here are the basics you'll need to decide for yourself.

Start with the bike manufacturer's recommendation in the owners manual or under-seat sticker. This is the number they consider to be the best balance between handling, grip and tire wear. Further, if you're running alloy wheels on poor pavement, consider adding 2 psi to the recommended tire pressure just to reduce the likelihood of pothole damage. Just as you would for a car, increase the pressure 2 psi or so for sustained high speed operation (or 2-up riding) to reduce rolling friction and casing flexing. Check your tire pressure regularly as they say.

In order to get optimum handling a tire has to get to its optimum temperature which is different for each brand of tire. Most of us don't have the equipment needed to measure tire temperature directly so we measure it indirectly by checking tire pressure since tire pressure increases with tire temperature. Tire temperature is important to know because too much flexing of the casing of an under-inflated tire for a given riding style and road will result in overheating resulting in less than optimum grip. Over-pressurizing a tire will reduce casing flexing and prevent the tire from getting up to the optimum operating temperature and performance again suffers. Sliding and spinning the tires also increase tire temperatures from friction heating.

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 ride on your favorite twisty piece of road. Then, measure the tire pressure immediately after stopping. If the pressure has risen less than 10% on the front or 20% on the rear, the rider should remove air from the tire. 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. The rear tire runs hotter than the front tire, 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.

When I used the tire pressures recommended by Ducati (32.5F/36R) for my 916 on my favorite road, I got exactly 10/20% on a set of Bridgestone BT-012SS. So I guess I'm an average rider and the BT-012SS runs at an average operating temperature compared to other brands.

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 same temperature (and pressure) that 35/39 psi gave you for the street. Don't even think about running these low track cold pressures on the street.

Finally, dropping tire pressures on street tires for track use has its limitations, so street compound tires on the track often get too hot and go beyond sticky to greasy. That's why you have race tires. Race tire compounds are designed for severe operation at these higher temperatures for a limited number of thermal cycles. On the other hand, race tire on the street usually won't get up to the appropriate temperature for good performance. At street speeds, the race compound often won't perform as well as a street tire.
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