Variable Tire Pressure

[CorsairMac]

I couldn't find a thread that addressed this - might've been too impatient to go too far back. My tire says proper PSI is 40-65 lbs. So - is that 40 lbs?, 50 lbs, 65 lbs? How do I determine? I pumped it up to 55 coz I wasn't sure what the wide range was for. Anyone got any ideas? Its a Trek Navigator 200 commuter bike with Bontrager (sp) commuter tires. I use it on roads and bike trails - paved. The tubes are thorn resistent with Slime. (New Mexico is Famous for Goathead thorns!)

[Dogmama]

Hire PSI = less rolling resistance & a bumpier ride

Lower PSI = opposite of above. Also better for slippery conditions

[spazzdog]

but lower PSI sometimes leads to pinch flats.

My roadie tires ask for 120 (or 130?) PSI.

I remember those goatheads! Ouch!

[SadieKate]

Dogmama is right, but also factor in the temperature on pavement. Hot asphalt can make the tire pressure go up very fast and then, as my hubby just said, "kablooey!"

I rarely ride any of my tires pumped to the max because the ride is can get very harsh unless it is a cold day.

[Dogmama]

Spazz is right - pinch flats can happen at lower psi's. For that reason, I always run max psi in my road bike tires and almost max in my mt. bike. Also, it helps with rolling resistence - although the ride is stiffer. The answer to the stiffer ride OBVIOUSLY is ... NEW BIKE! YEA!

[CorsairMac]

well - I went to almost max - 60 psi with a max of 65 psi and what a ride! WHEEEEEEEEEEEEEEEEEEEEE hit 23.1 max sp on my way to work this morning. I also had a 5 mph tailwind - but I'm gonna pretend it was my higher tire pressure! I'm real anxious to see the difference when I ride home tonight up the mountain! I'm Very excited! Thanks Yet Again for everyones help/advice/words of cheer!

[SadieKate]

Ok, I'm going to jump in with one more point just because we should make this topic as complex and confusing as possible!

Running close to max on a mt bike can be good and bad. Good for preventing pinch flats, bad for losing traction. If you are running a full suspension bike you can run lower PSI. Lower PSI can make the tires bite into the trail better. Higher PSI can make you bounce off the obstacles. Plus, you have to factor in your weight. That same good feeling of low rolling resistance on a road bike isn't necessarily so good on a mtb. You kind of have to play around with PSI till you find an optimum range and then adjust for trail conditions. I also don't pump up my tires until I reach my destination. Here in Calif I live at 25 feet above sea level but with a 2 hour drive be over 7,000 ft.