Many people ask this question, but the answer is not as simple as one might think. Tires replacement according to government estimates is when the tires are worn down to the wear indicators. What are tire wear indicators you ask? Wear indicator tires are small bumps in between the tread of the tire used as an indicator of tire life. However, there is more involved than just wear indicators. If you hardly drive your vehicle, the issue is you may want the check for is tire dry rot. This is when the tire starts to crack withered with age or is not used. We often see this in the trailers.
When inspecting tires always look for cracks in the tires. The general rule is that if you put the head of a dime in any crack, then the tires are not good. Another thing to look for is irregular tire wear. Irregular tire wear is usually the strengths and weaknesses of the tire. This is usually caused by a vehicle being out of alignment. It is always good to have your alignment checked at least once a year. If you live in rough terrain where there are holes, it is advisable to do it more often.
When it comes to adjusting a lot of people ask can I keep running the tires after I have my car aligned?. The answer is that, as long as the tires have not been worn down to the tire wear indicators, however, have it in mind that once you get the alignment of your car can hum or ride rough due to the wear, it will be up to you if you can handle it or not.
Winter tires or winter tires are other problems; many people do not realize that once winter tires greater than 50% or so life they are no longer consider snow tires. The tread has worn down too far and traction is no longer there. It depends on where you live on rather you can still be using them or not. I know people who wear the remaining tread during the summer. Note that the compound of snow tires is very different, so snow tires wear out quickly in the summer time.
When you go on a trip is another thing you should check whether it is perforated or holes. Note that a nail can escape into your tire, and it will not leak. This can lead you into trouble on the road. Many times the nails in the tires do not run away immediately, but after driving for a while they work into the tire more, or the nail hole gets bigger. It is better to have them fixed up when you notice them. When it comes to nail as long as they are small, enough tire plugs are fine, and when it comes to bigger nails, an internal tire patch is needed. Remember never let anyone patch or plug sidewall of the tire, which is totally dangerous and should not be done.
In the end, I want to advice that you should check your tires before planning a trip. You can also use a spray bottle mixed with water and soap to clean the tires to look for the leaks.