【How-to】Are 215 or 235 tires bigger

Sometimes, letters precede the first number. A “P” stands for p-metric, which is a tire used primarily on passenger cars. An “LT” indicates a light-truck tire. A “T” means it’s a temporary spare. … By definition, all W- and Y- rated tires are also Z-rated, though not all get a “Z” embossed on the sidewall.