Tires: Mismatched tires?, tire treadwear, gear ratios


Question
One last question on this topic, if you don't mind. Given the similarity in tread pattern and 8/32" remaining on the tires, can I replace only one tire with Michelin x-ice i2, or MUST I replace two tires? The mechanic has ordered only 1 replacement, so I'd like to know if I should instruct him to order a 2nd. Thanks!!

Answer
Vivian,
As I am not sure about the performance characteristics of the X-ice and the newer X-ice version (aside from the obvious speed rating difference, and fact that the new tire will have more tread depth), I recommend that you place a call to Michelin Consumer Relations.
Here's what the Rubber Manufacturers Assn. says (although this is a U.S. organization, The Rubber Assn. of Canada -- RAC --is sure to be in harmony):
[quote]REPLACING ONE (1) TIRE:
Replacing a single tire on a vehicle can have adverse affect on suspension systems, gear ratios, transmission, and tire treadwear.  If single tire replacement is unavoidable, it is recommended that the single new tire be paired with the tire that has the deepest tread and both be placed on the rear axle.  Placing greater traction on the rear axle on wet surfaces is necessary to prevent a possible oversteerr condition and loss of vehicle stability.[unquote]
As you can see from the above, single tire replacement is not the ideal scenario, however budgets do not always allow for the best solution.  I would prefer to see two matched new tires on the rear for optimum safety and performance.  Feel free to contact Michelin for a second opinion.
DT





http://www.rma.org/
http://www.rubberassociation.ca/Welcome/Welcome.html