Slightly underinflated is better than slightly over?

[Grey Thumper]

Got a tip that I'd like to check with you guys. A friend said that if there was a recommended pressure range for your tire (say, 38-42 psi for one rider with no pillion, no luggage), the tire will last longer if it's inflated to the lower end of the range.

I have to admit, this theory makes some sense, since the bike's weight will be distributed over slightly larger contact patches, but then, it also means a larger area is experiencing friction with the road. Anyway, given my not exactly light weight, I've always tended to inflate to the higher end of the range though. Watcha think?

[totalmotorcycle]

This should provide a lot of answers for ya:

http://totalmotorcycle.com/photos/tire- ... reTech.htm

http://totalmotorcycle.com/photos/tire- ... reTech.htm


Tire Inflation


Motorcycle tire inflation and contact patch area



Always keep the motorcycle manufacturer's recommended air pressure in both tires. This is an important requirement for tire safety and mileage. Your motorcycle owner’s manual will tell you the recommended cold inflation pressure. On some motorcycles, the recommended front and rear tire pressures will be different. The pressures stamped on the sidewall of the tire are only for maximum loads. On some occasions, these pressures will also be the manufacturers recommended settings as well.

Riding on tires with too little air pressure is dangerous. The tires will build excessive heat. This can cause a sudden tire failure that could lead to serious personal injury or death.



Underinflation may also:

-Damage the tire leading to tire failure
-Adversely affect vehicle cornering
-Reduce tire life
-Increase fuel consumption
-Fatigue cracking


Riding on tires with too much air can be dangerous. The tires are more likely to be cut, punctured, or broken by sudden impact. Serious personal injury or death could result. Do not exceed the pressure indicated on the tire sidewall. Consult your owner’s manual for the recommended inflation and other tire information.

Never inflate a tire unless it is secured to the motorcycle or a tire-mounting machine. Inflating an unsecured tire is dangerous. If it bursts, it could be hurled into the air with explosive force resulting in serious personal injury or death.

[agraebner]

before any other commentary, let me state that, A motorcycle manufactures recommended pressures are for use with the original equipment tires. Different models or tires require different amount of air, even to do the same job. So The best thing is if you are using the bike as the manufacture designed it in its stock form then follow the manufactures numbers. Once you start changing the type of tire on your bike then you have to adjust the air pressure to the needs of the bike (its load included) and the tire both. This takes some amount of figuring as well as close monitoring of tire wear and condition. MY general rule of thumb is figure out what percentage of inflation the bike called for with the OE tire and start with that percentage for the new tires max inflation. This is a good method for landing in the ball park. From here watch the load on the tire and its wear pattern. With these methods I was about to put 22,000 miles on a set of Metzeler 880 tires on my shadow. The original Dunlop's lasted only 6500. When i just sold the bike they measured at half the tread they were when installed, with perfectly even wear. The traction and ride were incomparable to the OE tires. PLEASE PLEASE PLEASE watch the condition of your tires. DRY ROT KILLS !!!! Many people do not understand that the NEW tires they just had installed on their bike last year could have been 5-15 years old. Rubber starts to deteriorate when its born. I have seen a lot of people riding deadly looking tires with deep splits in them due to this. They argued with me that the tires were new and fine....... If there are any cracks in the tire that allow you to see the chords in the tire replace it immediately. Dry rotted tires can degrade very quickly. The night hawk I just got has "NEW" Bridgestone's on it that were never ridden. In 200 miles they had cracks deep enough that I could see the chord was even rotting. Now I have a set of Michelin's on it and its AMAZING how this bike rides and handles. Tire technology has changed so much in the last years many of us should consider talking to a tire manufacture for tire recommendations. (especialy on an older machine) In my case I was told by Michelin themselves that I should take of my bias ply and go to Their Pilot road 3 tires which are radials. The tire manufacture knows what there tires do best. The perfect example... Ford and Firestone. Ford used a tire that wasn't rated for the application. The tire would have worked fine at 42 psi but they lowered the inflation to 32 to make the vehicles pass safety tests. In doing so they lowered the tires ability to do its job to below the weight that was really on the tires and they failed. I personally trust those tires and I have never seen a problem with one of them that was properly installed and inflated within its specifications.

[storysunfolding]

It won't change the rate of wear, just the wear pattern. You're not going to see extra miles from being slightly below.

I'll agree with agraebner that the OEM tires were the ones for which the manufacturer sets the air pressure sticker. However, many tire dealers have a portion on their website giving ideal pressures for different tires on different bikes. That's been my best resources for a good starting point.

[HYPERR]

Tire temps go up more with lower pressure.