I was checking the front tire pressure, as I had a slight shimmy, and everything seemed ok. I got another tire gauge, and pressure was 5 lbs off. I then got a third gauge, that I thought was probably the best one of the 3. Got 15 lbs in it, and rode 50 miles and all seemed ok. I then got to thinking, first one said everything was good, if I hadn't had 2 others, I'd have believed it was ok. Is there any way to calibrate a tire gauge ? Or who makes a good one. By the way, after I got 15 in them, I checked them with 1 and 2 gauge again, had 20 and 25, need a good accurate one.