how to tell when you need new tires on the tow vehicles

Tire Service Life
Cooper recommends that all tires, including full-size spares, that are 10 or more years from their date of manufacture, be replaced with new tires.
[FONT=Myriad Pro Light,Myriad Pro Light]Tire service life is not determined by chronological age. The useful life of a tire is a function of service and storage conditions. For each individual tire, this service life is determined by many elements such as temperature, storage conditions, and conditions of use (e.g., load, speed, inflation pressure, impacts and road hazard damage) to which a tire is subjected throughout its life. Since service and storage conditions vary widely, accurately predicting the service life of any specific tire based on calendar age is not possible.
Cooper Tire is not aware of scientific or technical data that establishes or identifies a specific minimum or maximum service life for passenger and light truck tires. However, Cooper recognizes a consumer benefit from a more uniform, global industry-wide approach to the tire service life issue. Accordingly, Cooper recommends that all tires, including full-size spares, that are 10 or more years from their date of manufacture, be replaced with new tires. Tires 10 or more years old should be replaced even if the tires appear to be undamaged and have not reached their tread wear limits. Most tires will need replacement before 10 years due to service conditions. This may be necessary even if the tire has not yet reached its tread wear limits.
Under no circumstances should a "maximum" service life recommendation for a tire be considered as an "expected" service life. Tires must be removed from service for several reasons, including tread worn down to minimum depth, signs of damage (cuts, cracks, bulges, impact damage, vibration, etc.) or signs of abuse (underinflation, overloading, improper repair, etc.).
In some cases a vehicle manufacturer may make a recommendation for tire replacement earlier than 10 years for their products based upon their understanding of the specific vehicle characteristics and application. If so, the consumer should follow those vehicle manufacturer’s specific recommendations for their vehicle.
[/FONT][FONT=Myriad Pro Light,Myriad Pro Light]For additional information, see Cooper Service Bulletin #

Thats a good sample. The reason is pure saftey. There is no "Law" as described here in. Just Xp of those in the know. I stand by what i said from my Xp as mechanic. Towing even on a proper load range tire is still a lot of stress. Most people wait till they have a blow out from what I see.
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