Tire Pressure Valve Caps - 36 lbs. - set of 4 Take the pressure out of knowing when your tires are filled to their optimum levels. Its a simple system. When tire pressure has reached its maximum normal level, our valve caps show green-a go for better fuel efficiency, increased tire longevity and smoother ride. When the green recedes, its time to get your tires checked. No more guessing. No more worrying. Screw-on caps replace existing valve caps in a snap: no tools required. Available in two pressure levels appropriate for most cars, pick-ups, vans, SUVs and CUVs.