As horse lovers, we probably don't often think of tires as related to our passion, yet, if you haul your horse anywhere, then tire condition is very important. And with high gas prices, it's even more so. You should check your truck and horse trailer tires at least once each month. In fact, this advice pertains to tires on all vehicles.

First, check the inflation. If a tire has a maximum inflation pressure of 40 PSI, then inflate it to the 35 - 40 PSI range. Do this in the morning before driving anywhere when the tire is cold. Keeping your tires properly inflated will make the tire ride properly for maximum traction and long life as well as save gas, and both long life and less gas saves you money.

Second, inspect your tire tread for wear. You can use the penny trick and stick the side with Lincoln's head into the tread — if you can see the top of his head, the tire is no longer safe and should be replaced. If the top of his head is buried in the tread, the tire has more useful life left.

Third, have a mechanic examine tires that make excessive noise or vibrate while driving. It may be that the wheel just lost a balance weight that can quickly and inexpensively be replaced. It could also be that a tire lost a piece of rubber and is about to blow or was malformed at manufacture and is defective.

Fourth, inspect the tire for cuts or cracks. Cuts can occur from the tire hitting a sharp metal object, such as another truck, trailer, a fence, a post, and many other things, or from intentional vandalism. Cracks in the sidewall result from dry-rot and will not usually leak air, so you may think the tire is fine, but it's really not because the cracked part of the tire wall is weakened. Believe me, you don't want that tire to blow when you're cruising down the highway with your horses in tow.

For those that like to know how natural processes work (I do), dry-rot can occur from several factors:

1. Exposure to Ultraviolet Light
   Tires are black because they contain carbon black as a sacrificial stabilizer to inexpensively absorb UV by converting it to heat. The problem is that the absorber gets exhausted and when that happens, the tire wall starts cracking and will often turn gray. That tells you the tire is at the end of its life, even if it was not used. Other absorbers exist, but are more expensive, though they could provide tire walls of almost any color — I won't pay extra for it — I'd rather buy tack.
2. Exposure to Atmospheric Ozone
   Tire manufacturers add other compounds to protect against ozone. The ozone does attack these compounds, but they're renewed by working their way to the tire surface by tire flexing during normal use and provide a barrier. When the protective compounds are exhausted, or a tire is not used for a long period of time (like when trailers stay parked), the ozone can attack the rubber itself which will dry, check, and then crack.
3. Heat – As in many chemical reactions, heat acts as a catalyst contributing to accelerated tire degradation. Heat comes from several sources:
   • Climate – Tires degrade faster in warmer climates.
   • Hard Driving – Driving quickly over rough surfaces causes more side-wall flexing. Such flexing causes heating in the rubber of the tire.
   • Under-inflated Tires – Driving with under-inflated tires also causes more flexing and consequent degradation.
4. Oils and Solvents
   Petroleum products can dissolve the protective compounds and, well, you now know the rest. So if you're riding through puddles of petrochemicals (oils, cleansers, or any solvents) or are applying chemicals to make your tires "shiny", you may be removing the aforementioned compounds designed to protect the tire and we again have tire deterioration.

Besides being an avid trail rider, Jerry Tardif is a technology consultant and a horse and nature photographer in SE Connecticut — see his work at: www.jerrytardif.com. He is also co-founder and President of QueryHorse.