1. Unscrew the valve cover
2. Make sure the pointer returns to zero
3. Pressure can be measured in 2s 

Mechanical design Gives you no fear of digital failure works perfectly in all weather conditions without batteries Metal pressure measuring valve Rotate 360 degrees Rubber sleeve Large dial Small and easy to carryFor accuracy, check pressure when tires are cold. Pressure increases with heat. Tires can lose one pound per month under normal conditions. Proper tire pressure improves gas mileage, handling, braking and durability.

item	Tire pressure gauge
Size	12.2 x 6.2 x 3.5cm
Application	for SUV RV CAR TRUCK
Certification	CE Rosh FCC
Pressure range	0-220psi
Material	Steel, Aluminum ,Copper,Zinc Alloy, Plastic,Rubber
Accuracy	1.5psi
Working temperature	-15 to 60℃
Display	LCD Digital Display
Brand	Win Glitter
Model Number	Y-T025
Warranty	12 Months
Package Type	Product size: 12.2 x 6.2 x 3.5cmNet weight: 158g Sliding blister Gross weight:185g Dimensions of package:20x11x3.5cm Dimensions of master carton:40*28*31cm 80pcs/ctn G.W.: 17.kgs N.W.:15kgs