Question: What does a smooth suspension, 350-hp engine, sophisticated stability control, and massive brakes have in common?

Answer: They're only as good as the tires they ride on.

No other part of your vehicle connects you to earth, yet truck buyers look at engines, tow ratings, room, and gadgets, assuming proper tires are already part of the deal.

Cavemen probably didn't realize the ramifications of inventing the wheel. Progress has developed the simple concept into a more complicated object that's partially responsible for every aspect of vehicle dynamics, ride, safety, traction, and economy. The following primer isn't meant to make you an expert, but rather to equip you for coherent conversation with your tire specialist, because what you don't know could literally, well, you know.

Sidewall Hieroglyphics
The first pneumatic tires on an 1896 production car were simple things unencumbered by heat requirements because nothing went faster than a brisk bicyclist. Modern tires and the machinery they run on is more complex, so a wealth of information is printed on every street-legal tire sidewall. Certainly, many people look for the name and outlined white letters, but that's the least-important writing there. From the alpha numerics on a tire, you can tell what size it is, how much weight it'll carry, up to what speed, what it's made of, where, when, and what the government thinks of it.

Virtually every tire size on the market today may be expressed as metric, ISO metric, or flotation (inches). Metric and ISO metric differ mainly in where the load rating is listed. A P-metric designator is the same as ISO metric except that a P (for passenger car) precedes the size. LT (light truck, LT265/75R16E, for example) tires are similar, except that the load rating is a letter, just as it appears on flotation tires.