Let’s take another look at our tire information:

P255/50R16

This means we have a P-metric general passenger type tire with a 255mm section width.  Nothing fancy so far.  Continuing down the line, we see that the profile is 50% of the section width, which puts it at 127.5mm.  Note, the smaller the third term in the string the lower the profile of the sidewall will be.  Thus, if you’re looking for a low profile tire, or slicks as some people call them, you’ll be looking for a very low number to occupy that space.  Especially if they’re a very wide tire.

When looking at a tire for a truck, people generally want a higher third term for a taller tire, where width isn’t so much of a factor.  But due to manufacturing processes and engineering, you’re generally going to find a higher second term as the profile gets higher.

This brings us to the fourth term, which tells us what the internal construction of the tire is.  I get asked all the time if this separates a cheap tire from an expensive tire, and the answer is always no.  The internal construction of the tire has very little to do with price, since most tires in this day and age are R-type, or radials.

What this means is that the tire construction is a series of rubber plies that radiate out from the center of the tire where it fits around the rim.  In other words, imagine that there are 10 layers of rubber from the outside surface of the tread to the inside where the pressurized air is held.  If you were to cut the tire drop top to bottom to look, it would almost look like a horseshoe.

Other constructions that you might see are D for diagonal, or bias-ply, where the plies of rubber are laid at a 90 degree angle to each other, diagonal across the tire as it would travel on a vehicle.  B indicates belted, which is similar to bias-ply construction except it is reinforced with belts under the tread area.

More than 95% of all tires sold today are of radial construction, cheap tire or expensive tire.