tire pressure question

spearx wrote:

Where did you find the operating pressue info? I looked around the bridgestone website and did not find that info.

After I got a new set of tires I noticed a little wobble in the rear on corners and certain streets. I was inflating the tires to the 41 PSI per the number on the side of the tire, but I (205#) was the only one riding. After reading this thread and others I lowered the pressure to around 30 PSI and that seemed to calm the wobble feeling in the back. I just wondered why stamp a number with load specs on the tire if that is not the correct number?

One other thing - my spitfires are stamped next to the size as 11R not the S11 listed on the website?

Any help you can offer.:ohmy:

S11 is the tire model, it's not required to be on teh sidewall, I'm not sure what the 11R is.

The pressure molded on the sidewall is the correct pressure to carry the weight that is stated right beside it
It says "Max Load xxx lbs at 41 psi" so if the weight on your rear tire is xxx then it should be inflated to 41 psi. If the actual weight on the rear tire is 50% of xxx, then it should be inflated to a little over 50% of 41 psi.

Personally, I intially inflate the tires to whatever the manual calls for, then I adjust the pressure up or down until I get the handling and ride that I want. Then I maintain the pressure at that number.

Sigh... the maximum air pressure is two fold. First it is the mfg.'s recommended max air pressure for the design of the tire as a "tire". In otherwords the mold to application. (Worked with Goodyear guys a few years ago on tire molding)

The second point is the rating for max speed. How this plays out is that the mfg. has detemined a safety factor into the equation. Most pressure vessels have a 4 to 1 factor for under stress conditions.

What does this mean for you? Use the tire mfg's recommendations. If you fail to do that expect scaloped tires or lots of road rash!

I just wanted to say thanks for all the info. The tire pressure was an issue with the way my bike was riding.

Riding much better - still needs a little work (fork seals) and she will be ready for a season of riding.

Thanks again