||08-08-14 03:27 PM
Originally Posted by Sierra
Yes, that reminds me of another reason I went with the larger tires. I'm running the original Weinmann rims which do not have hooked beads. The tires want to blow off at 90 psi, so I keep them at 80 psi.
run mine at less then even 80 but I weigh 165 with cycling clothes on...but I run more when I put a load on to tour and my touring kit weighs around 35 sometimes 40 (weekend only tours) plus another 25 pounds for the bike so say 230 pounds total I only put in 80 (I like about 5 psi more which I do all around) in the rear and 65 on the front. This calculator: Bicycle tire pressure calculator
shows how to figure it, I use the 700x32 size for my 27" tires and since most of my touring weight is on the rear I change the F/R% to 45/55. Anyway the point is if you are riding with more or less weight you need to adjust your pressure accordingly, so if I ride with just my body weight and the bike's which would be about 190 and change the F/R % to 40/60 then the PSI drops to 55 front and 66 rear (again I like 5 psi more).
The above figures keep the tires drop ratio to around the idea 15% drop that has been widely recognized as the best drop to use for most types of riding and for most types of tires. Some tires may require more psi than the calculator shows so you have to look at the tire packaging and see if they recommend anything different. The reason why some tires require more psi and tell you so is because one, they know about the 15% drop rule, and two, their tires drop a bit differently than most and thus using the standard calculation will cause their tire to drop too much.