wmtire

I don't know if I ever explained the differences between sizing systems of the metric sized tires and the Euro-metric tires before. If I did, then please ignore all this boring stuff below:

OK, the Goodyear Marathons that come on our trailers are sized in what's called simply enough "metric" tire sizing. Tires can be "P" metric , "LT" metric, or "ST" metric (which the marathons are). The P, LT, or ST designate the type of tire use, but the numbers behind that designation mean the same.

Just using the 14 inch tires for example, our trailer tires are ST215/75R14.

This means this tire is a "Special Trailer" (ST) use tire. It is 215 millimeters wide when loaded at it's normal carrying capacity (this is the space between the bulging parts of the sidewall, and not the actual tread width), the sidewall is 75 percent as tall as the tire is wide when at it's normal carrying capacity. It's a Radial (R) constructed tire and it fits a 14 inch rim.

These ST tires can come in 4, 6, or more plies, which will be designated by a Load Range letter of B, C, or higher. This Load range letter won't be in the sizing, but somewhere else on the tire.

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Ok, now the tires that many of us are trying on our trailers are sized in what's called Euro-metric sizing or Euro tires as I call them. This sizing system is a little different.

Most everyone is trying an Euro-sized tire that is 195/R14C

The 195 means the tire is 195 millimeters wide.

Now note, that there isn't an aspect ratio number, which was 75 in our tire above. Euro-sized tires of this type don't put the number in their sizing. If they did, it would be an 82. This means our Euro tire is actually a 195/82R14C if we tried to make it come out to the same metric numbering system as our 215/75R14 tire above. Because this tire is 82 percent as tall as it is wide, it gives it more sidewall to stand up to the heavier loads.

It's a Radial (R) constructed tire and goes on a 14 inch rim.

Now to the C after the rim size. It's easy to confuse this for a Load Range letter, which it is not. In our Euro-sized tire, this C means it is a commercial rated tire used in heavy hauling applications. It would be similar to our "LT" or "ST" designation used above. It's just at the back of the size instead of the front

These Euro Tires will also have a Load Range designation letter located somewhere else on the tire. These tires will likely have a C, D, or higher. Most everyone is using a D (8 ply) rated tire.

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Now that we know the difference in the tire sizing used for the tires, we can also understand why our metric ST215/75R14 is practically the same height as the Euro-metric 195/{82}R14C tire..........and works easily as a replacement. 75 percent of 215... is close to 82 percent of 195.