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justoneoftheguys wrote:What about the % rule (I forget what % is used).

But you start with cold tires, at your best guess. Go for a long ride and warm them up. Stop and check the pressure when they are warm. If they show too much pressure increase, I believe that means the tire pressure was too low to begin with. (Tire flexing causes heat that causes air pressure to rise.)

If your pressure check shows no increase in pressure, they were probably too high to begin with.

All, feel free to critique my logic.

Major Softie wrote: I don't think anything is wrong with your logic, but your recommendation has a rather large hole in it. Exactly what is "too much pressure rise?" That is the crux of your recommendation.

Tire pressures go up 10-15% when they're warm, so if you started at 36 and rode for 20 minutes, they will probably be between 38 and 40 PSI. You'll need to add or lower the pressure from that pressure, and not from the original 36!

Major Softie wrote:

dwerbil wrote:
Thank you, but I'll keep doing that. I've used the factory psi my entire life....on my cycle tires, car, truck, wheel barrow, what ever. Up to and with in a few psi. The factory psi on the sidewall is perfect info Major for what to run, as it always says to "Never exceed". Otherwise, wouldn't you say one is just guessing.

Edit to add...seems most all cycle tires have a never exceed of 40 psi front and back, as far as I recall.

I'm sorry dwerbil, but you are quite simply incorrect. If you trust the manufacturers so much (a perfectly reasonable trust), then just check their sites, and they will inform you as to your error.

In addition, may I correct my earlier statement about it being the maximum pressure for the tire. That was incorrect as well. I believe there was a time when tires showed max. inflation (as bicycles still do), but that is definitely not the case now. Now, the pressure on the side of the tire is the pressure at which their maximum load rating has been tested. If I may reference the Avon Motorcycle Tires "Tires 101 for Consumers" .pdf document:

A tire inflation pressure is on the sidewall of every tire showing a tested pressure under load. This is neither the recommended pressure nor the max inflation.
http://www.avonmoto.com/download/Tires1 ... sumers.pdf

In other words, the only thing the pressure on the sidewall tells you today is that this is the pressure at which the tire was tested in reference to its maximum load rating.


On your second point (in your edit) exactly zero of the 8 mounted motorcycle tires in my possession list 40 lbs as their max load rated psi.

Tim Shepherd wrote: What do you think? Should I be running higher pressures than 32 front 34 rear??

Tim Shepherd wrote:I check my tire pressures regularly, but when I took it to be inspected last time, the guy said my front tire showed signs of having been "way under inflated for a long long time". He pointed out that the outer two thirds were worn out, while the center one third of the tread was not. I took this with a grain of salt considering; 1: I always check my tire pressures, 2: I ride hard and lean over in the twisties, 3: Bridgestone Spitfires are supposedly a harder compound in the center for longer life, and lastly, 4: he was working at a Harley dealership, and likely never saw tires that had been leaned in a turn... What do you think? Should I be running higher pressures than 32 front 34 rear??

Tim Shepherd wrote:I check my tire pressures regularly, but when I took it to be inspected last time, the guy said my front tire showed signs of having been "way under inflated for a long long time". He pointed out that the outer two thirds were worn out, while the center one third of the tread was not. I took this with a grain of salt considering; 1: I always check my tire pressures, 2: I ride hard and lean over in the twisties, 3: Bridgestone Spitfires are supposedly a harder compound in the center for longer life, and lastly, 4: he was working at a Harley dealership, and likely never saw tires that had been leaned in a turn... What do you think? Should I be running higher pressures than 32 front 34 rear??