2015 Q70 tire size

[xjokerz]

So I bought a used 2015 Q70 with about 55,000 miles on it a few months ago. It doesn't ride badly, but I was curious about increasing the comfort level. If I go to a bigger sidewall, will this be done? My current tires are 255/40R20 and if I changed the 40 to say a 50 or a 55, is that possible? Thank you.

[Larz]

You are right in considering the effect of sidewall on the ride comfort. I went from the OEM 245/45 to 255/40's and there is no noticeable difference in ride comfort or road noise. The benefit of using the wider 255 size is all about handling and grip. The size of the sidewall had no effect, but going from a 40 to 50 sidewall is two sizes higher which might actually make enough difference to soften the ride quality. You will still have the same OEM suspension, so it's hard to say if it will make a big difference though. Changing to adjustable aftermarket struts might be an idea, but very expensive and may void any warranty you have.
Remember this: Right now, your car is at the OEM spec'd ride height. That ensures the car will drive, steer, and handle at optimum performance and safety. If you keep the same wheel size, you must keep the ratio of (sidewall height / tread width) the same to maintain the OEM ride height: (265/35) = (255/40) = (245/45) = (235/50). If you want a size 50 sidewall, you will need to use a 235 tread width. 235/50/20's can be found on Land Rover, some Jag XJ-L's, etc so they certainly won't be dangerous or inappropriate for a Q70 sedan. They will, however, be more expensive and probably available only from higher quality brands like Michelin, Pirelli, etc.

[Malbec 56 Beast]

That's a lot of good advice.
Actually the factory sport tire size is 245/40/20.
245/45/20, 255/40, 255/50 or a 235/50 might be an option.

The one thing that I don't think was brought up was the actual tire brands. Mich, Bridge, Perelli Continental (I have), those should give you a very nice and comfortable ride.

I put 275/35/20 on my sport wheels and it rides very very nice. My winter setup has 235/55/18 winter tires and they are real comfortable as well.

If you don't love the 20" sport wheels you could always get some 18's and do a size like or similar to my winter setup.

Good luck
Let us know what you decide

Andy

[Mjkkb2]

I put 275/35/20 on my sport wheels and it rides very very nice. My winter setup has 235/55/18 winter tires and they are real comfortable as well.

If you don't love the 20" sport wheels you could always get some 18's and do a size like or similar to my winter setup.

Good luck
Let us know what you decide

Andy

Andy,

Are you on stock suspension, wheels? Thinking about getting wider on the rear but don't want it too rub.....

[kmiles]

Will 18" Infiniti wheels fit if his Q70 has the sport brakes? I have a 2015 Q70, too and upgraded to the 20" wheels. I've been thinking about upgrading to the larger sport brakes, but I understand that I couldn't use the 18" wheels with winter tires if I do that.