Originally Posted by LeeG

I’m with dabac that it’s the bikes geometry but 65-75 psi seems a tad low for 1 1/8” tires if you’re not a light person or carrying a rear load, The tires max pressure has no bearing on optimal pressure. 65-75 is more what I’d use for 1 1/4” tires but again it all depends on the weight the wheels are carrying. There’s a world of difference between optimal psi range for unloaded riding or loaded riding esp. for the rear tire. When I was light and light touring on 1 1/8” tires I’d pump the rear to 80psi figuring it would be down to 75 in a couple days. One time touring with 1 1/4” rear and 1 1/8” front I just pumped them to the same psi.
When I had my shop in the 80’s it was interesting to see the ranges of psi people toured on. Folks on 25 mm tires touring on 120 psi, others on 1 1/4” with 45-60 psi. “Did you know your rear tire has 50psi?” , “I thought it was soft, I filled it last week”