[Keracticus]

Hi,

I've got a 2014 F31 with the OEM 17" Pirelli run flats and recently fitted ACS springs.

I'm looking to change to either 18" or 19" wheels and go flat tyres. I'm considering OEM sizes in a staggered set up. The changes are purely aesthetic.

I know going up in wheel size negatively impacts the ride/comfort. But at the same time go flats should give a better ride than the run flats.

Does anybody have any experience changing from 17" run flats to 18" or 19" go flats and could offer an opinion on the change in ride characteristics.

KP

[chowser51]

How are your roads maintained?

I went from 18” run flats to 17” go flat snow tires. Love it. Then I went to 19” go flat summer tires. It’s okay but the roads keep denting/curbing my wheels. Once these treads wear out I am switching to 18” go flats.

[Keracticus]

Originally Posted by chowser51

How are your roads maintained?

I went from 18" run flats to 17" go flat snow tires. Love it. Then I went to 19" go flat summer tires. It's okay but the roads keep denting/curbing my wheels. Once these treads wear out I am switching to 18" go flats.

Thanks for your input. That's what I want to avoid! Sounds like you were ok with the ride of the 19s but they pick up damage easier. I'd say most of the roads I use are ok, but I'm in the UK and there are plenty of poor roads. A greater risk of damaging the larger wheels isn't some thing I'd considered.

KP

[J555]

Originally Posted by Keracticus

I know going up in wheel size negatively impacts the ride/comfort. But at the same time go flats should give a better ride than the run flats.

That's correct, however, there are more factors affecting the result, as:
- rim weight - the less weight the less work for dampers
- tire sidewall - more sidewall provides more comfort
- tire diameter - the bigger overall diameter makes the wheel falling to pothole less
- tire model - a noticeable difference in comfort within the same tire sizes
- tire weight - similar to rim weight, the lighter tires make the ride comfier

If you stick to oem sizes for staggered setup, you should focus on rim weight and tire model/weight. I suggest to google the forum for the pictures of cars fitted with the same sizes and similar chassis as your car. If 18" meets your goals in terms of aesthetics, they are indeed the choice of comfort.

For UHP tires, the best combination of low weight and comfort is obviously either Goodyear Eagle F1 Asymmetric 5 or Michelin Pilot Sport 4, closely followed by ContiSportContact 6. Worth to have a look also at Falken Azenis FK510, as quite many consider it a more comfortable tire and still a good performer.

If your lowered springs allow and you are fine aesthetically, you can still consider going one level up with tire profile. Granted, the higher sidewall noticeably helps comfort.

Regarding the change, if you do it properly, you can expect the smoother ride and more pleasant experience even going up 1" inch. In general, the non-rft tires absorb especially the sharp bumps and potholes much better. While not sure what are your current Pirelli's, any of the top 3 brands should improve the overall handling. On top of that, you have much less risk of damaging your rims.

[Keracticus]

Originally Posted by J555

That's correct, however, there are more factors affecting the result, as:
- rim weight - the less weight the less work for dampers
- tire sidewall - more sidewall provides more comfort
- tire diameter - the bigger overall diameter makes the wheel falling to pothole less
- tire model - a noticeable difference in comfort within the same tire sizes
- tire weight - similar to rim weight, the lighter tires make the ride comfier

If you stick to oem sizes for staggered setup, you should focus on rim weight and tire model/weight. I suggest to google the forum for the pictures of cars fitted with the same sizes and similar chassis as your car. If 18" meets your goals in terms of aesthetics, they are indeed the choice of comfort.

For UHP tires, the best combination of low weight and comfort is obviously either Goodyear Eagle F1 Asymmetric 5 or Michelin Pilot Sport 4, closely followed by ContiSportContact 6. Worth to have a look also at Falken Azenis FK510, as quite many consider it a more comfortable tire and still a good performer.

If your lowered springs allow and you are fine aesthetically, you can still consider going one level up with tire profile. Granted, the higher sidewall noticeably helps comfort.

Regarding the change, if you do it properly, you can expect the smoother ride and more pleasant experience even going up 1" inch. In general, the non-rft tires absorb especially the sharp bumps and potholes much better. While not sure what are your current Pirelli's, any of the top 3 brands should improve the overall handling. On top of that, you have much less risk of damaging your rims.

J555. Thanks for your comprehensive input. I hadn't really appreciated tyre mass as a variable and just assumed they would all be similar! But I'll focus on your suggestions when looking for tyres.

I've now spent even more time reading through loads of threads and looking at the price of tyres. I'm changing my mind! I think an 18" square set up would suit me. I like the look of a square 245/40 R18 set up and am not sure what I would get out of going staggered with 255/40 on the rear. In addition, 245/40 R18 seems to be a sweet spot for the price of tyres as well - often cheaper than both 225/45 and 255/40.

I've had a nagging doubt about clearances if I move away from standard specs for wheels and tyres. But from what I've read 18 x 8.5 ET35 with 245/40 should fit fine with no adjustments or tweaks required.

Is there anything I should be worried about with a square 18 x 8.5 ET35 with 245/40 set up?

KP

[Fez_7]

Originally Posted by Keracticus

J555. Thanks for your comprehensive input. I hadn't really appreciated tyre mass as a variable and just assumed they would all be similar! But I'll focus on your suggestions when looking for tyres.

I've now spent even more time reading through loads of threads and looking at the price of tyres. I'm changing my mind! I think an 18" square set up would suit me. I like the look of a square 245/40 R18 set up and am not sure what I would get out of going staggered with 255/40 on the rear. In addition, 245/40 R18 seems to be a sweet spot for the price of tyres as well - often cheaper than both 225/45 and 255/40.

I've had a nagging doubt about clearances if I move away from standard specs for wheels and tyres. But from what I've read 18 x 8.5 ET35 with 245/40 should fit fine with no adjustments or tweaks required.

Is there anything I should be worried about with a square 18 x 8.5 ET35 with 245/40 set up?

KP

Since you've done some research do you mind me asking why you feel a square set up would suit you perfectly apart from price?

I'm running 18x8 front, 18x8.5 rear staggered with 225/255 at the minute, could I switch to the same square set up you mentioned without changing rims and if so, what are the pros and cons?