I agree with everything except what I put in bold. Again a load rating of 93...you are asking for trouble. My summer wheels on my Q are 255-35-20 97Y where I needed at least a 95.Q45tech wrote:The manufacturers MINIMUM LOAD INDEX is 95 or the ability to support 1521 pounds on the 90-96 Q45.
Tires must have enough safety factor to cover the weight transfer in turning or braking when up to 1/3 EXTRA weight is placed on specific tires.
The front is always the most critical unless so much luggage is in trunk to negate the 56/46 static load.
For example the Q sitting still has 1080 pounds on each front tire, add a driver and the LF gets ~half the divers weight depending on seat fore/aft position. That could be 1180 [with 200 lb driver].
During braking up to 300 extra pounds per tire gets added if full tank of gasoline more if back seat passengers or trunk item even more.
The other problem is the tire is rated at 1521 pounds under maximum inflation that would be 51 psi on modern tires.
When you undersiaze tires [load index] you greatly increase their wear rate and decrease their performance and safety.
But then anyone who would use a larger heavier than necessary wheel tire combo doesn't care about safety or wear rate.
Something in a 17 or 18".