Posted by Roger on September 16, 1999 at 11:34:15:
In Reply to: Re: Re: correct information on reversing tires> whitewall in posted by Mr. Parsegian on September 15, 1999 at 11:45:11:
In my opinion Tire Guy has muddied the water again. Sounds like lots of theory but not real application from tire engineer's viewpoint.
Most tires do not have construction different on one side as opposed to the other. Construction here being the internal body ply and reinforcement not the external white or black rubber compound.
A small % of tires, which are usually High Performance, (V speed or faster) are identified with stamping on the sidewall as directional. DAVE pointed this out in his post to your original question.
The majority of these "directional" tires are only considered directional because of their tread pattern which is has slightly better water dispersion when run in one direction.
Again there is a small percentage of these "directional" tires which have different construction on one side. This is done primarily for improved handeling. I have not seen and would not expect, for DOT approved street tires, any tire durability issues to be of concern if you chose to deviate from the recomended direction of rotation other than you would not get the optimum perfromance that you paid for with a directional tire. I have raced on directional tread pattern tires running in the dry with no loss in performance.
If the tire does not say "This Side Out" or have a direction of rotation arrow molded into the sidewall is is safe and acceptable to mount so that the tire rotates in either direction. In my 30 years as a tire engineer I do not recall a White sidewall tire with a unique body construction on one side which would affect its performance or durability in running one direction or the other.
To answer your specific question "are some tires constructed different then other tires? "
YES some are different than others. In fact almost every tire has a unique construction but that doesn't mean it is unsafe as long as you follow the instructions provided for that tire by the MFG.
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