AboutBarry Smith Expertise I have over 30 years experience in the design, manufacturing, and
testing of tires. I have served as the technical advisor to the "800"
number. I have authored or co-authored many publications - usually
without credit. I can answer almost any technical question, but
please don`t ask me to compare brands. I probably have prejudices because of
my work experience.
Experience Member SAE (Society of Automotive
Engineers)
Member Tire Society (Tire Technical Organization)
SCCA Regional Competiton License holder
Authored many training manuals on tires, their care and use.
Expert: Barry Smith Date: 6/15/2008 Subject: Tire Rotation Questions...
Question I have seen the recommendations to put 2 NEW tires on the rear of the car, if only buying two tires.
OK here is the question that is bugging me...
I want to get my tires rotated. And I happen to have 7/32's on the front and 8/32's on the back. Should I rotate, or should be go with the "2 NEW tire theory" and keep the rear tires where they are at. Thus, pretty much negating the need for Tire Rotation work because most cars that come in for a rotation have the better tires on the back, because everyone knows tires tend to wear faster on the front?
Of course in a perfect world the tires should have been rotated before allowing them to get to mis-matched tread depths.
Thanks,
Jeff
Answer Jeff,
The difference between tires with 7/32nds and 8/32nds is so small that it doesn't matter.
The "New Tires on the Rear" recommendation is directly towards situations where there is a substantial difference between the tires - and we're generally talking about 4 or 5/32nds vs new of 10 or 11/ 32nds. The whole idea behind this recommendations is to prevent the tire from hydroplaning (or losing traction on show) with the rear tires first - and you have to have tires that are quite different for it to make a difference.
Plus, most folks like simple to remember rules - and this is one - as opposed to complex rules with exceptions and variations. Keep that in mind when you are reading about tires. Most of the rules and recommendation are designed to be simple and easy to remember, but there are some exceptions to the rules, and if you want to know what those exceptions are .... well ..... that's why I'm answering questions.
