Key Tyre Marking Description
A Manufacturers or brand name, and commercial name or identity.
B Tyre size, construction and speed rating designations. Tubeless designates a tyre which requires no inner tube. See tyre sizes and speed ratings below. DIN-type tyre marking also has the load index encoded in it. These go from a load index of 50 (190kg) up to an index of 169 (5800kg).
C Denotes type of car tyre construction.
D M&S denotes a car tyre designed for mud and snow. Reinforced marking only where applicable.
E Pressure marking requirement.
F ECE (not EEC) type approval mark and number.
G North American Dept of Transport compliance symbols and identification numbers.
H Country of manufacture.
DOT Codes and the 6-year shelf life
As part of the DOT code (G in the tyre marking above), there is a tyre manufacture date stamped on the sidewall. Oddly this code is sometimes only one one sidewall so you might need to get under your car and look at the inward-facing side of the tyre. Take a look at yours - there will be a three- or four-digit code. This code denotes when the tyre was manufactured, and as a rule-of-thumb, you should never use tyres more than 6 years old. The rubber in tyres degrades over time, irrespective of whether the tyre is being used or not. When you get a tyre change, if you can, see if the tyre place will allow you to inspect the new tyres first. It's not uncommon for these shops to have stuff in stock which is more than 6 years old. The tyre might look brand new, but it will delaminate or have some other failure within weeks of being put on a vehicle.
Reading the code. The code is pretty simple. The three-digit code was used for tyres manufactured before 2000. So for example 1 7 6 means it was manufactured in the 17th week of 6th year of the decade. In this case it means 1986. For tyres manufactured in the 90's, the same code holds true but there is a little triangle after the DOT code. So for this example, a tyre manufactured in the 17th week of 1996 would have the code 176triangle
After 2000, the code was switched to a 4-digit code. Same rules apply, so for example 3 0 0 3 means the tyre was manufactured in the 30th week of 2003.