increase the wall size on a F06 GC Tyre

[BmwF06Ireland]

Hi Guys
i want to move away from a runflat
and the options for the OEM tyre size on the back is shocking

275 30 20

if i look at the next size 275 35 20 the option are endless,

what repercussions are a potential for changing the size?

car is totally standard

rubbing?

speedo?

ride comfort increase ?

has one one done this and regretted it ?

regards

ronan

[Opie55]

Is your car XDrive?

[jackliu0527]

I went with 255/35/20 FR and 295/30/20 RR, tires being wider increased the side wall a tiny bit, but I also have M5 rims to fit the wider tires in the back

[BmwF06Ireland]

Originally Posted by Opie55

Is your car XDrive?

nope standard f06 640d

It has the 20" 373m.. standard wheels


Took a chunk out of wheel and tyre last weekend and want to.put non run flats on the back

[BmwF06Ireland]

Originally Posted by jackliu0527

I went with 255/35/20 FR and 295/30/20 RR, tires being wider increased the side wall a tiny bit, but I also have M5 rims to fit the wider tires in the back

they look like.pilot sports, are the non run flats

[FinalRenegade]

Non run-flats will improve your ride quality 100%, its night and day difference

I couldn't believe it when others posted that swapping to non-RFTs made a major difference, but my M6 ride quality is way more comfortable than my 650

go get some pilot sports!

[Qsilver7]

Originally Posted by BmwF06Ireland

want to.put non run flats on the back

If you don’t already know...mixing different types of tires and/or tire treads can create instability in certain circumstances and other peculiarities. If you’re only going to change the rear tires...then stick with what you have. If you want to move away from run flats...then do all 4 tires.

In regards to increasing the sidewall...do a google search for tire upsizing which will explain how to use tire sizes other than the ones recommended by the car manufacturer. You want to stay within specs of the overall tire circumference...which is how you can run 18/19/20 inch wheels/tires without any issues.

There are sites like www.tirerack.com that give alternate tire sizes if you enter your vehicles info when looking for tires...you can safely select form those given tire sizes that have a higher sidewall. You’ll also need to consider the width of your wheels, too. Because as the sidewall height (aspect ratio) increases...the width of the tire needs to decrease. Again, if you go to a site like TireRack.com and enter your vehicle’s info...it will give a list of alternate tire sizes that should fit the OE wheels that came with your car.

[TGrits10]

Originally Posted by BmwF06Ireland

Hi Guys
i want to move away from a runflat
and the options for the OEM tyre size on the back is shocking

275 30 20

if i look at the next size 275 35 20 the option are endless,

what repercussions are a potential for changing the size?

car is totally standard

rubbing?

speedo?

ride comfort increase ?

has one one done this and regretted it ?

regards

ronan

I went to 265/35/20 non-runflats out back, wanted to match the fronts I had put on earlier but that tire wasn't available in 275/35/20 and anything bigger than that would've made my speedo read low. At this size it reads only slightly high now, like 1+ mph at highway speeds. Next round I'll go to a different tire and likely do 285/30/20 out back.



You can absolutely run a mix of RFT & non-RFT, and/or different brand/model tires front/rear. Yes there are slight differences in feel/handling/grip, but not enough to matter, the only noticeable difference is ride comfort, which I can confirm is muuuuch better with non-RFTs! The thing you don't want to mix is side-to-side, front/rear is standard practice unless all 4 tires magically wear out at the same time.


Anyway the conventional wisdom is to stay within 3% of the stock diameter to keep from upsetting traction/stability systems, going from 30 to 35 profile is a pretty significant jump in those terms, hard not to exceed 3%. I went down a tick in width and I think the overall increase came out to about 2%.



I haven't had any TCS/rubbing issues, my speedo is closer to accurate, and the ride is a whole lot better. Only issue is I think it looked a little better with the shorter sidewall, but that's a subjective opinion, not a technical concern

[elvisisdog]

245/40/R20 up front
275/35/R20 rear

All tyres replaced at the same time for P4S from Dunlop run flats.

You need to watch the front strut as this gets pretty close to the top of the tyre. On the tyre combination above it's within 5mm. I get no rubbing at all and had the tyres on nearly 2 years. No issues with traction control or abs. I'm massively impressed with the P4S they just don't seem like they'll wear out and have excellent grip, wet weather ability and durability.

Downsides, kind of obvious but the car feels slower to accelerate but can still break the wheels free on spirited driving. The car feels way more vague and squidgy in corners. Speedo is out slightly, although i I've had no issues in the UK with average speed cameras, specs, gatsos all sticking to speed limit with car right on the button. In honesty it probably reads close to true speed.

I'm running standard 373 rims and was expecting the tyre wall increase to reduce the crash over potholes and manhole covers. It probably does but I actually miss the firmness in the corners of the run flats.

Would I do it again, probably not, although what I really want is 21 inch rims as I generally feel the wheel well looks a little too large for stock tyres and rims. I know I could lower it but in honesty I think a larger wheel suits the car.

[BmwF06Ireland]

Originally Posted by TGrits10

I went to 265/35/20 non-runflats out back, wanted to match the fronts I had put on earlier but that tire wasn't available in 275/35/20 and anything bigger than that would've made my speedo read low. At this size it reads only slightly high now, like 1+ mph at highway speeds. Next round I'll go to a different tire and likely do 285/30/20 out back.



You can absolutely run a mix of RFT & non-RFT, and/or different brand/model tires front/rear. Yes there are slight differences in feel/handling/grip, but not enough to matter, the only noticeable difference is ride comfort, which I can confirm is muuuuch better with non-RFTs! The thing you don't want to mix is side-to-side, front/rear is standard practice unless all 4 tires magically wear out at the same time.


Anyway the conventional wisdom is to stay within 3% of the stock diameter to keep from upsetting traction/stability systems, going from 30 to 35 profile is a pretty significant jump in those terms, hard not to exceed 3%. I went down a tick in width and I think the overall increase came out to about 2%.



I haven't had any TCS/rubbing issues, my speedo is closer to accurate, and the ride is a whole lot better. Only issue is I think it looked a little better with the shorter sidewall, but that's a subjective opinion, not a technical concern

I am going to just get 1 x dunlop to match the other side and change alloys early next year

Have to get the rim refurbished also. Big ding.

Thanks for the info..

[kingwest01]

Originally Posted by elvisisdog

245/40/R20 up front
275/35/R20 rear

All tyres replaced at the same time for P4S from Dunlop run flats.

You need to watch the front strut as this gets pretty close to the top of the tyre. On the tyre combination above it's within 5mm. I get no rubbing at all and had the tyres on nearly 2 years. No issues with traction control or abs. I'm massively impressed with the P4S they just don't seem like they'll wear out and have excellent grip, wet weather ability and durability.

Downsides, kind of obvious but the car feels slower to accelerate but can still break the wheels free on spirited driving. The car feels way more vague and squidgy in corners. Speedo is out slightly, although i I've had no issues in the UK with average speed cameras, specs, gatsos all sticking to speed limit with car right on the button. In honesty it probably reads close to true speed.

I'm running standard 373 rims and was expecting the tyre wall increase to reduce the crash over potholes and manhole covers. It probably does but I actually miss the firmness in the corners of the run flats.

Would I do it again, probably not, although what I really want is 21 inch rims as I generally feel the wheel well looks a little too large for stock tyres and rims. I know I could lower it but in honesty I think a larger wheel suits the car.

Is your car an xi ? I have a 2013 650xi GC. Wonder if the 275/35/R20 would fit in rear?

[kingwest01]

Gents would someone please help me if this configuration would work on 650xi 2013.. im scepitcal on ET:

Specs:

Front: 20x9 ET 20 Hub bore: 74.1mm

Rear: 20x10.5 ET 27 Hub bore: 74.1mm

[Luftpost]

Originally Posted by kingwest01

Gents would someone please help me if this configuration would work on 650xi 2013.. im scepitcal on ET:

Specs:

Front: 20x9 ET 20 Hub bore: 74.1mm

Rear: 20x10.5 ET 27 Hub bore: 74.1mm

Start here. This will answer your ET question, since ET is often subjective.

L

[Qsilver7]

Originally Posted by kingwest01

Gents would someone please help me if this configuration would work on 650xi 2013.. im scepitcal on ET:

Specs:

Front: 20x9 ET 20 Hub bore: 74.1mm

Rear: 20x10.5 ET 27 Hub bore: 74.1mm

The problem won't be so much the offset...but you will need to use hub-centric rings to take care of the center bore which is larger than your wheel's 72.56mm hub. The wheels won't be centered on the hub without special care (due to the larger center bore)...and could easily become off centered if you hit a road imperfection hard enough.

Definitely run the specs you have above through the link Luftpost gave you in his reply (www.willtheyfit.com)..to the originally front & rear wheel/tire set-up originally on the car. This will reveal how much more "poke" or "inset" you will have with the new set-up vs the old set-up.

[elvisisdog]

Originally Posted by kingwest01

Is your car an xi ? I have a 2013 650xi GC. Wonder if the 275/35/R20 would fit in rear?

No, rwd. Although from memory when I was looking at this the rolling circumference was better than stock in terms of staggered wheels. It's relatively easy to check on those 'will they fit' links below.

As long as your in 1% you should be all good on the xdrive.

Shouldn't be any issues on the rear. Upfront the difference on xdrive is the front strut which is shaped more like a tuning fork to allow the drive shaft through. All of that is way out the way of the wheel, so I'd have thought you should be all good.

[itzjoker]

Originally Posted by elvisisdog

245/40/R20 up front
275/35/R20 rear

All tyres replaced at the same time for P4S from Dunlop run flats.

You need to watch the front strut as this gets pretty close to the top of the tyre. On the tyre combination above it's within 5mm. I get no rubbing at all and had the tyres on nearly 2 years. No issues with traction control or abs. I'm massively impressed with the P4S they just don't seem like they'll wear out and have excellent grip, wet weather ability and durability.

Downsides, kind of obvious but the car feels slower to accelerate but can still break the wheels free on spirited driving. The car feels way more vague and squidgy in corners. Speedo is out slightly, although i I've had no issues in the UK with average speed cameras, specs, gatsos all sticking to speed limit with car right on the button. In honesty it probably reads close to true speed.

I'm running standard 373 rims and was expecting the tyre wall increase to reduce the crash over potholes and manhole covers. It probably does but I actually miss the firmness in the corners of the run flats.

Would I do it again, probably not, although what I really want is 21 inch rims as I generally feel the wheel well looks a little too large for stock tyres and rims. I know I could lower it but in honesty I think a larger wheel suits the car.

Would you mind posting or PM a picture of your car with the above tire set up?

Found a great deal on some wheels/tires combo:

20x8.5 ET35 - 245/40/20 F
20x10 ET40 - 295/35/20 R
Michelin PSS


I'm currently on OEM 20" M Sport set-up with 1.2" drop in front, RWD. No issues whatsoever, but I am afraid I might run into problems with this new set-up. I've read that fronts will fit with stock suspension.

Would appreciate any suggestions. Thanks!

[jackliu0527]

Originally Posted by BmwF06Ireland

they look like.pilot sports, are the non run flats

those are PS4S, and yes they are non-rft

[elvisisdog]

Sorry for the late response, I'm not on this forum that much these days.

I've taken a few pictures, my tyres are probably 50% worn but on stock 20" rims and all fits without any rubbing. The front upper control arm is the part that is of interest but at these sizes you have a good 5mm clearance and I've not had any issues at all.

My car is filthy and the light isn't helping much, wheel is slightly turned but provided a measurement from rim edge to upper fender. It should give you an idea of the diameter difference and the impact of lowering springs.