I was hoping someone could give me a quick response. I recently bought a Tekton tire gauge, which is used primarily for cars but was considerably cheaper than the gauges for bicycles. (Everything for cycling is twice as expensive for some reason..)

It only has a schrader valve which is the only downside. Anyway- to my question. I've been inflating my tires based only on how difficult it is to push down on the tire. When I get little resistance I consider that close to the maximum pressure the tire can handle.

Well as it turns out, repeatedly checking the pressure with the gauge showed that assessment to be way off. What I was considering enough tire pressure is measuring 35 PSI??

I'm using Schwalbe Winter Marathon tires which actually can't handle a lot of pressure, they run at 85 PSI max.

I'm having a difficult time pumping air into them around 35 PSI with my hand pump.

IS THIS NORMAL? I would hate to blow up my inner tube because the gauge was wrong!

I have noticed that when I get on the bike, the tire does sag quite a bit. And I have noticed that it seems it takes a great deal of effort to pedal around, and the bike slows quickly while coasting. This seems to corroborate the tire gauge's readings, that the tire is woefully underinflated.. Which would mean for at least 2 years I have been biking on tires at half the pressure they needed to be.