STEP 1# GROUNDWORK There's a sidewall on the side of the tyre that lends it stiffness. While a taller, softer sidewall can absorb bumps better, a shorter, stiffer one has better cornering ability and more agile steering response. On the sidewall of every passenger and light-truck tyre is an alphanumeric code -a 'P' or an 'LT' - describing its dimensions, and some even have a maximum load indication. While selecting new tyres, make sure the coding matches the ones you are replacing.
STEP 2# BUY THE WAY Speed rating translates into the tyre's ability to dissipate heat, or prevent heat build-up. The more the heat, the faster it wears out and breaks down. A tyre with a higher speed rating can dissipate more heat on long highway trips. So, if scaling highways is what you are looking at, focus on the speed rating T (118 miles per hour or 189.9 km per hour) and H (130 miles per hour or 209.2 km per hour).
STEP 3# TECH TALK Before you splurge, check the air pressure and sidewall linings of each tyre. The new breed of run-flat tyres contain air and are much more complicated in construction than early rubber rings. However, they are also tough enough to run without air if necessary. In a stiff-sidewall run-flat tyre, there is extra reinforcing rubber that prevents the sidewall of the tyre from deflecting. The sidewall is no stiffer than a conventional tyre in an inner-liner run-flat, but a hard rubber or plastic ring inside it helps keep the sidewall from deflecting.
STEP 4# FUEL FOR THOUGHT Depending on the tyre you select, you will see a 15 to 20 per cent difference in fuel economy. Drivers should keep in mind that the fuel economy is dependent on proper air pressure. Air pressure should be monitored once a week, going by inflation pressures usually outlined in the vehicle owner's manual. This ensures maximum fuel economy.