masonpb

Realize it varies depending on the surface, temps, conditions, etc but curious on the general rule of thumb for knobby tires on the road vs on dirt/gravel. Thanks.

rithem

don't forget body weight ...

masonpb

Thanks...145 lbs. Was thinking 30psi for dirt/gravel and 60 for road?

Fat Boy

Tire size?

rithem

30 would be ok for your weight for a clincher, for racing ... you could go as low as 20 or even 18! on a tubular. For every day riding >30psi probably fine.

obrentharris 

In my part of the world where 'cross courses often have concrete curbs, tree roots, broken rock, and hard-packed dirt, 30 pounds in clinchers will get you a pinch flat in no time. 50 pounds would be more reasonable but, unless you are very light on the bike, you'll still get the occasional pinch flat... Number one argument for racing on tubulars.
Brent

simonaway427

I'm 160lbs on a 17lb bike.

I ran 35f/38r psi on my 34mm clinchers last year for racing. I bottomed out lots on roots and curbs, but never pinch flatted - although I'd imagine it would have been a matter of time.

I'm on tubs this year, planning on 28-32psi for those.

I run 50psi if i ride on the road on those tires. Nice compromise between comfort and rolling resistance.

rithem

rule of thumb on racing pressure, you should bottom out without pinch flatting once or maybe twice per lap --- it's all about being smooth and picking good lines, 50 psi will make a wreck of your corning skills in short order.