For starters, a tire sidewall will tell you everything: the brand, model, basic dimensions. You can even figure out your tire's birthday. The following illustration shows the information that can be found on most tire sidewalls:
Aside from the fact that it offers a variety of key facts, it's important to keep that tire sidewall in good condition. Though not always the case, any protrusions or cuts (or anything else compromising the condition of the tire) can cause performance issues if not monitored. You'll want to read "Sidewall Separations/Bubbles"
and "Sidewall Indentions, Undulations and Protrusions
" for more information.