kap1

This may be a dumb question, but I have ContiExtreme DWS on my A4 (235/45R 17). Got a pothole flat the other day, have been using full spare from my old set Goodyear Eagles LS2 (also 235/45R-17). The tread on all 4 matches almost exact, 4-5/32. Would rather just wear out this set and buy another 4 in 1-2 years. Do I need to spend $175 to replace the one Conti ? what happens if I just leave as is ? I haven't noticed any significant driving differences, though haven't been at high speed yet only local driving. Thanks for any thoughts.

Reggie

The correct answer is that you will affect the handling - as the two tires will have different characteristics. Is that a significant difference.- probably not for normal driving. The right thing to do is to buy one Conti and have it shaved to the correct depth as the existing tires so you don't cause issues with the diff.

brya6

Like Reggie said, you might damage your diff depending on the remaining tread depth. This is in your owner's manual: "rolling radius of all 4 tires must remain the same or within 4/32" of each other in remaining tread depth."