Most consumers don't understand how important having the proper tire can be-it really can mean the difference between life and death. When choosing replacement tires, it is crucial that they meet or exceed the specifications dictated by the vehicle's manufacturer. If planning on going up in size, either on the stock wheel or larger aftermarket wheels, it's good idea to ensure the new size conforms to tolerances set by the manufacturer (see the requirements placard typically located on the vehicle's door jamb). It's also important not to change the rolling diameter too much, because drastic changes can throw off a vehicle's traction control systems, braking and acceleration, even the navigation system. A good rule of thumb is not to exceed plus/minus three percent.
There's a lot more to a tire than its size. While proper sizing is important to make sure the aforementioned systems aren't affected, the following tire ratings are the ones that keep you safe.
Uniform Tire Quality Grading (UTQG) is a system used by the government to ensure all tires are graded equally in three separate categories: treadwear, traction performance and temperature resistance. This prevents individual manufacturers from making claims that cannot be substantiated and helps consumers make a more informed decision when purchasing tires. All tests are performed at government-specified laboratories and test tracks under controlled conditions.
Most drivers never look at their tires unless there is a severe problem. Drivers and mechanics will often misdiagnose vehicle performance issues when the problem could be attributed to worn or improperly inflated tires. When experiencing reduced fuel economy, sometimes a tune-up is in order, but often the tires will be under-inflated. Other problems associated with tire issues can include rough ride and reduced braking ability.
Research is priceless when it comes to selecting tires. If replacement tires carry the exact specifications as stock, you're covered. If there are any differences, make sure they're on the plus side and that you correct the cold inflation pressure to match the characteristics of the new tire. To maintain peak fuel economy, optimal wear and trouble-free operation, it's a good idea to check cold inflation pressure as often as possible, being sure to make corrections for weather and altitude changes.