Tire Pressure

[tricyclerob]

Hi all, I could be opening a bag of snakes here, but what tire pressure opinions are there out there? I have a '59 R-69, w/Michelin 100/90 on the frt and 110/90 on the rear. I just re-mounted my Ural s/c, and looked in owners manuel for the pressure. It indicated 27psi for s/c, but 21.3 frt, and 27 rear, for occupied s/c. But, forget the s/c, I usually run 34 frt and 36 rear running the bike solo. I know tire tech. has improved in 50 yrs, but 21 and 27?? Actually the shop manual for solo use indicates 19.9 psi frt and 24.1 rear. Wasup??? thanks, rj

 

[dlearl476]

IMO, tire pressure, within reason, is a personal choice and the values you'll find bandied around are simply suggestions, starting points.

As far as tire wear goes, I think the 10% rule* is pretty good advice. But in certain situations more or less might be best, for you. It's all about YOUR comfort level, after all.

*Hot tire pressure is cold tire pressure + 10%. I.E. if you're looking at 30 psi cold, once your tires are up to temp, they should be 33 psi. Less, remove air, More, add air.

In my experience, every tire is different and remember the "ratings" molded into the tire are MAX pressures only.

 

[20774]

As far as tire wear goes, I think the 10% rule* is pretty good advice. But in certain situations more or less might be best, for you. It's all about YOUR comfort level, after all.

*Hot tire pressure is cold tire pressure + 10%. I.E. if you're looking at 30 psi cold, once your tires are up to temp, they should be 33 psi. Less, remove air, More, add air.

I had heard about this rule before. On a set of tires a while back, I decided to find the tire pressures according to this rule. I ran the same path from my house, same speeds, approximately the same outside temperatures, and same bike configuration. I tracked the hot and cold pressures in a spreadsheet. The net result was that I was going to have to exceed the cold sidewall pressures in order to meet the 10% rule. I believe the stiff sidewalls of the newer tires is what was entering into the problem.

I have since reverted to manufacturers recommendations. Not the old manuals as they represent old tire technology. I basically run 32 front and 36 rear, changing the rear slightly if I'm carrying additional loads or a passenger.

 

[72598]

test

just a test

 

[72598]

Harley (need a pre 69 manual) recomends F-24 R-27 S-22. Quite lower than two wheelers. Makes a big diff. over using higher pressures that are recommended for 2 wheels.