msandhu413

I am getting a chance to upgrade my 19inch; rims to 20inch with almost brand new tires from A8; but the tires size 265/40r20 - will this not advisable either (tires only have about 5k miles on them)?

Baloo588

I bought a set of 4 20s with 265/40R20 for my A8L and I wanted to test them on my A7 but the dealer couldnt fit it so no.

msandhu413

I just installed 20s with 265/40R20 - today on 2015 A7 ( they were from A8) and they fit perfectly. No rubbing at all.

Baloo588

I would NOT recommend you to use those tires. They are too thick and cause greater than 3% speedo error and will in the long run put strain on your transmission. You should be researching this up properly. Dump those tires and go down to 265/35/20 or 275/35/20.

msandhu413

Not too concerned about 3% speedo error - no big deal at all. Regarding the size - I will be replacing the tires with 275/35 in about year but for now 265/40 is only about 1 inch bigger than the 265/35.

19hole

The two numbers that you car about are Diameter and rolling circumference. The diameter matters as you may have interference with the bodywork. For these two sizes; the 265/40 is 28.35" in diameter, the 275/35 is 27.58". The difference is 0.77". Take half of that, 0.39", and that is how much more of the wheel well the tire will occupy.

The rolling circumference of the tire concerns us as it will change the speedometer/odometer calibration. For these two sizes; the 265/40 rolls 89.05" per revolution and the 275/35 rolls 86.64" per revolution. That means that the 265/40 rotates fewer times per mile by approx. 2.7 %. If you don't care about the speedometer/odometer then you should be ok as long as all 4 tires are the same.

msandhu413

Thank you for the clarification. Do you think it will be any problem with keeping 265/40 for a year or so; since it there is no rubbing (i'm ok with 2.7% speedometer error)?

tenspeed

I don't think that there will be any problem running a slightly larger tire if there is no rubbing.

I recently corrected my fuel consumption factor so the indicated MPG's were closer to the actual MPG's. There may be a way to change the distance factor with the VCDS that would change your speedometer and odometer.

Baloo588

Hows the gas mileage on the A7 on highway with those bigger tires? My dad did 255/45R20 on his 2012 Audi A8L when the standard was 265/40R20 you have and the gas mileage on highway dropped from 26-27 to 24 mpg and he was upset as the bigger rolling diameter cause the MPG to suffer due to heavier tire and more work on the engine so total cruising range dropped from 520 on all highway to 460 or so which is bad. We plan to take these off and put the 275/40R20 which is close to the 265/40R20 on the 2012 A8L to get that MPG back. When we put the standard 19s back on with winter tires in proper OEM tire the MPG went back up considerable so the over diameter jump was a bit too much even if it was within 3% speedo error.

As for the 2016 A7 I have the sports package and lower suspension with the 275/35R20 and the ride is great with good side wall protection without any MPG issues that the A8L had with the 20 inch summers and 255/45R20.

msandhu413

Have not seen any difference, yet. Mine is TDI - diesel power so difference may vary. My folks also own an A7 with 255/35R19 and now you mention the big difference your dad saw in the mpg after going bigger tires, i will definitely going to keep track of mpg change.