Tires – Inflation DOT Other Information

What do you know about your tires? – Tire information series

Inflation Pressures


Today in our series on tire information we will look at some more important information contained in the fine print on the side of your tires. Every tire has a rated maximum inflation pressure.  Often it will be found in small print around the rim edge of the sidewall.  It will say something like “Max. Load  670 kg (1477 lbs.) Max. Press. 340 kPa ( 50 PSI)”.  This means that the tire will safely carry up to 1477 lbs. and can be safely inflated up to 300 kPa (Kilopascal) or 50 psi (pounds per square inch).  Often the vehicle manufacturer will specify a slightly lower pressure on the door jamb sticker for purposes of ride comfort and handling performance.   For maximum tread life and fuel economy it can sometimes be helpful to inflate the tires to a pressure closer to the rating on the tire rather than the rating on the door jamb of the car, but doing this can sometimes negatively affect ride comfort and possibly traction.

DOT numbers and other information


Every tire sold in the US must have a DOT (Department of Transportation) number.  The DOT number is a safety certification number that includes information about who manufactured the tire and where and when (week and year) the tire was manufactured.  This number is useful if a recall needs to be made on a certain batch tires.  For potential recall or safety issues it is a good idea to register your tires with the manufacturer.  You can do this online or by sending in a DOT registration card (provided by your tire installer).

One other marking on some tires, is a directional marking.  Some tires are designed with a certain side of the tire intended to be mounted towards the inside or outside of the vehicle.  These tires will have either an “Inside” or “Outside” written on the tire and should be mounted accordingly.  Other tires are designed to provide good traction and treadwear only if operated in a certain direction.  These tires are called directional tires and have an arrow symbol or other marking on the outer sidewall of the tire indicating which direction the tire should be mounted for forward rotation.

Well, there you have it.  That covers the information found on most tires sold for passenger vehicles in the US.   Now you can be an educated consumer and impress your friends with your knowledge of tires.

If you are located in the Harrisonburg Virginia area – give us a call and we will be glad to help you choose the right tires for your car or light truck.