I should know better but I only relearned afterwards because precision is implied (numbers on the gauge going to tenths of a PSI) , which is the case does NOT mean accuracy. So when I gauge-inflated the rear dual tires to a cold pressure of 80.0psi, it turns out I was actually inflating them to 85+psi, which is especially problematic when the tires start to age (in my nearly 3 year old ). The over-inflation caused punctures and severe damage to a Class C motorhome for less than 3 years.