From what it tells me, I can safely put in 30 to 33 PSI of pressure in my Schwalbe Marathon GT 365 tires (26"x2") on poor roads. This would be below the min 35 PSI listed on the tire, and about 20 PSI lower than what I’ve ever run them at.
I’m not too terribly worried about punctures, but do worry about pinch flats.
I’ve found it to be pretty spot on for road/ gravel tires. Make sure you err on the side of sticking with the manufacturer minimums regardless of the recommendations from silica as theirs are more general and they don’t know exactly which tire/rim combo you’re running.
I think you’d be surprised how low you can get on some setups these days. I ride my gravel tires at 40 PSI (40mm tire) and I weigh 280lbs with a 305 total system weight. Given that you’re on a wider tire and I assume, smaller than me I don’t think you’d be pinch flatting on 35psi.
I may start running lower to see how it affects comfort. I know that when I’m below 50 psi, my tires get much louder, even though they are near silent on roads close to 60 psi. Maybe I’m worrying too much about pinch flats 😂
Measure your actual tire width and make sure you use the correct total system weight (body, gear, bike, water, etc.) I use the calculator all the time but I haven’t had it give me seemingly out of range answers like that before.
I’ve confirmed the tire width with calipers, and I overestimated the weight (added an extra 60lbs of load) to be on the safe side, but the number still look really low.
Even if I fiddle around with numbers, for example, increasing the speed from recreational to fast group ride, it changes the values by a half PSI.
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