Choosing Tires
Your tires provide traction and stopping power in fair weather and foul, so when shopping for replacements you need to be aware of the different types available.
As a general rule, you want as much rubber in contact with the road as possible. A larger contact area provides more grip, whether accelerating, cornering or braking. This is why race cars use slick tires. The problem with these for road use is that slicks don't remove water from the road surface. Instead the water gets between tire and road, resulting in a loss of traction. The grooves or tread on road tires break up this water and move it away from the contact area.
Tire design is a compromise between the differing requirements of rain, snow and dry conditions. Tires also have to handle the weight of different vehicles, from lightweight two-seaters to full-sized SUVs. This is why there are different tires for passenger cars and light trucks/SUVs and also for summer, winter, and "all season" motoring.
If you're tire shopping you'll know the type of vehicle, but it might not be obvious which "season" you should go for. That depends on how much you expect to be driving in rain and snow and whether or not you're willing to buy a second set of tires.
For most people "All Season" tires are going to do the job. If you live in a region that sees some snow but you don't want to invest in a spare set of snow tires, these are what you should buy. While not giving racing-style traction, they provide a compromise between grip in wet conditions and in dry and are also designed to cope with light snow. You'll recognize them by the "M+S" symbol on the sidewall.
If you're going to be doing more driving in snow, or in deeper snow, but still need reasonable dry-surface behavior, you could look at "Performance" or "Studless" snow tires. These are marked with a snowflake-on-mountain symbol. The primary difference between these and "All Season" tires is a bigger, blockier tread pattern. This helps clear snow, but on smooth roads it creates more noise and a rougher ride than the "All Season." Many drivers will want to take these off in spring to replace them with summer tires.
Someone who needs to drive in really bad snow and isn't concerned about dry road characteristics might want to get "studdable" snow tires. These should not be used on clear tarmac, and in fact, because they tend to be hard on road surfaces, their use is not permitted in some localities.
At the other end of the spectrum are the summer performance tires. These will provide the kind of sharp responses that a driving enthusiast craves, but only in dry conditions. In the wet they'll deliver very low levels of traction, so if you're using these you'd better have a spare vehicle available or live in the desert!
To summarize, your tires are one of the most important parts of your vehicle and need to perform under all conditions. When tire shopping, give some thought as to the conditions you expect to encounter and select the type that best meets your needs.
