Cy4Q7

Hi! I cannot seem to find this topic in a search but I am switching from the 6 spoke 18" OEM wheels on my wife's 2014 Q7 to the "double 5" spoke 20" OEM wheels. Is there anything in particular (besides the obvious new tires :-) ) that I need to have done to the vehicle prior to this? Computer flash? Suspension part of any kind? I don't *think* there is as I'm going with another size of OEM for the vehicle, but I want to double check and not assume.

Thank you!

madigral

I do this all the time as I run 18" winter tires and 20" summer tires. I just assumed when I did it and bought a second set of rims without checking and it just worked . However, what you should really be concerned about is overall tire diameter. You can calculate that using an online wheel/tire calculator, like the one found in the link below; here is the example of my two tire/wheel combos.

https://www.wheel-size.com/calc/?whe...cl=30mm&sr=0mm

If you scroll down the page, you'll see that the overall diameter only differs by 1%. I'd would have preferred this to be <0.5%, but 1% it totally fine. You'll also notice that this particular calculator will also show your speedo drift due to the change in tire circumference.

So, in short, no, as long as the overall diameter is relatively close, you should be good with no other supporting modifications.

Cy4Q7

Thank you for the reply! The calculator is nice and your scenario seems a lot like what I'm wanting to do with the two sets of wheels. Just an FYI, I got curious and found this calculator too... Tire Size Calculator - Tire & Wheel Plus Sizing

One thing that concerns me is that I know the speedo is already off by a roughly 2-3 MPH (too slow) so these bigger wheels/tires being even a smidge larger will increase that even more. I suppose I will just have to check out different speeds on the dash and how they match up to an accurate GPS...

Gavin0478

I run 21's for the summer on 295/35/21 and 18's for the winter 255/55/18 and there is no difference in the speedo calibration via gps.
As long as you stuck to the 275/45/20 size on the 20's as thats the factory size i would say you would have no issues.

Cy4Q7

Thank you as well Gavin0478! I'm feeling a lot better about this now. And until today had not realized that Audi has made use of indirect TPMS so no new sensors to buy for the second set either! That was nice news.

Greystoke

Are you looking for Summer or an A/S tire?
Grey

Cy4Q7

Hi Grey. I'm honestly not sure if I am going to go with a set of A/S tires for the new 20" wheels or go more with a summer only tire. I haven't decided if I am going to sell the 18s yet or not... I keep going back and forth on it. :-)

Greystoke

Where are you located? In the snow zone it would be ideal to get a good set of summer tires for the 20" wheels and a set of snows for the 18" wheels.

Grey

Cy4Q7

I'm in Iowa, soooo.... Ideally I should be keeping the 18s and getting a good set of snows. That is what I do for my car. But I'm also thinking that the Q7 seems to handle so well on the snow and ice that the A/S set might be sufficient. Also not sure I'll be able to talk the wife into going back to the 18s even just for a few short months in the winter...