What tire pressure should I use for my bike? When I usually ride, I notice that my rear tire is squashed about 50%, but when I try and squeeze the tire, its rock solid. (All riding will be on streets)

My bike is a Trek 820 Mountain Track with 'Invert 2' tires (26 x 1.5). I weigh about 220 lbs. It says on the tire to inflate to 45-85. I normally inflate them to about 65 or 70. Should I go up to the 85 limit? Or is some squashing of the tire to be expected with my weight? I feel like if I inflate it that high, it will blow out when I sit on it...

I have a 50-mile bike ride this weekend, and I am trying to work out any bugs before then so that it is as smooth a ride as possible. (Last year, I couldnt figure out why it was such a difficult ride and everyone was blowing past me until I finished it and was pushing my bike and noticed my rear brakes were dragging. I'm not gonna let something stupid and simple like that ruin my ride this year.)

 

65 to 70 lbs. is plenty. I am 205 and I ride with 50 to 60 lbs depending on whether it is road or dirt.

 

If it is sagging, up the pressure.

I'm 220 too and run 45 front, 55 rear off road and 105f 110r on my roadie.

I sag quite a bit on my mountain bike, but ride on a lot of sand, so like it that way.

I don't put up with any sag on my roadie...

 

You should really stick to manufacturers recommendations with regards to pressures: all pneumatic tyres from wheelbarrows to sports cars. The "appearance" of sagging is not due to low pressure but do to the nature of large air volume tyres (and tubes) - it's intended for superior grip off-road. Obviously rider weight is also a factor. If it's cosmetics you are worried about bit smaller section tyres (and tubes) and inflate them accordingly. Good luck.