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For those of you that don’t believe in rotation of tires I hope you like buying transfer cases on all wheel drive vehicles. All of the AWD vehicles built since the 1990’s can be damaged by a .5 inch differential in rolling circumference from the largest to the smallest tire on the vehicle. Many of the active AWD systems built since the early 2000’s can be damaged by as little as a .125 inch differential from larges to smallest tire. I have personally rebuilt/replaced transfer cases that have burned up clutches in as little as 15,000 miles because the customer failed to have the tires rotated causing excessive differential in rolling circumference. Not selling a rotation at every oil change on an AWD vehicle is doing your customer a disservice.
Tall assumption on your part how you think of those that understand the difference. We check LOADED diameter and have yet to have a single transfer case failure due to tires. Sets that don’t meet our loaded diameter tolerance are brought to the customers attention. You may wish to revisit your specs.
Thanks for your comments none the less.
My specs come straight from Chrysler engineering. Loaded or unloaded circumference makes no difference in the real world. The same amount of rubber for each tire has to roll down the road each time the tire goes around which ever way you measure it. I have literally had to deal with hundreds of Chrysler, Ford and Volvo AWD systems with shudder complaints since the mid 1990’s. Nearly all of them were traced back to mismatched rolling circumference of tires. Some could be fixed by just putting a good set of matched tires. Most either needed a viscous coupling replacement or t/case overhaul. In drastic mismatch cases I have seen ptu’s blown apart dropping pieces as they rolled of the flat bed that delivered them to the shop. Do what you want with your customers. I will recommend to mine what I feel will do best to prolong the life of their vehicle.
