Anyone moved from 19" run flats to 19" non run flats?

[Vintage]

Originally Posted by Rafale

Excellent questions!
1) Noise and tramming difference should be negligible.
2) Our Speedo are offset by 3-5%. BMW explains that they did it this way to anticipate people increasing tire size... how weird! All you will be doing is to make the speedo more accurate.

I am going 1 size up in the front (235) and two sizes up in the rear (275). According to the specifications it is the widest I can go on 8" and 9" rims and I know people who did much bigger without rubbing. Should get the tires this Friday.

Confirmation - I went a one size on all four with 19" wheels with factory offset. We have a 35i with the Sport package. No rubbing issues. However, whether you stay stack or up-size, you can't go wrong. Please post your thoughts after the new tires are on and you have done a little driving.

[dr_mikee]

Originally Posted by Vintage

Confirmation - I went a one size on all four with 19" wheels with factory offset. We have a 35i with the Sport package. No rubbing issues. However, whether you stay stack or up-size, you can't go wrong. Please post your thoughts after the new tires are on and you have done a little driving.

so you what size tires did you use for your squared setup?

[Rafale]

Originally Posted by Vintage

Confirmation - I went a one size on all four with 19" wheels with factory offset. We have a 35i with the Sport package. No rubbing issues. However, whether you stay stack or up-size, you can't go wrong. Please post your thoughts after the new tires are on and you have done a little driving.

Well,

as I posted before I went with the same size with PS2s 3 years ago on my 30i (18") and it made a huge difference in terms of both comfort and handling. I did not upsize at the time because the 18" wheels are 8" front and 8.5" rear so it did not leave any room to go wider in the rear.

Now on the 35is with 326 wheels, I am able to upsize to the way I want and with PSS, it is even better, turns are crisp, less sliding and ohh so many of those rattle sounds went away.

[HerrK]

Originally Posted by dr_mikee

so you think we can run this same Porsche S setup with our wheels and tires?

No Porsche sizing for the Z4 - I wouln't go bigger that 225/40x19 for the Frt. The 265/40x19 (R) would be way too large OD and would rub for sure.

Go to Tire Rack all the specs are there.

[dr_mikee]

Originally Posted by HerrK

No Porsche sizing for the Z4 - I wouln't go bigger that 225/40x19 for the Frt. The 265/40x19 (R) would be way too large OD and would rub for sure.

Go to Tire Rack all the specs are there.

for some reason dimensions for 2013 z4 isnt up there...and it only gives you exact sizing for stock dimensions not a squared setup or a larger fit....

[Rafale]

Originally Posted by dr_mikee

for some reason dimensions for 2013 z4 isnt up there...and it only gives you exact sizing for stock dimensions not a squared setup or a larger fit....

I am really not sure what you are trying to do there. Tirerack, for a given car will only give you the stock settings. What HerrK was referring to is that you can look up the tire specifications for different sizes on Tirerack. In order to do that you just have to look up the tire size by entering it manually. If you look it up by car, obviously, they will just tell you what the stock sizes are...

[dr_mikee]

Originally Posted by Rafale

I am really not sure what you are trying to do there. Tirerack, for a given car will only give you the stock settings. What HerrK was referring to is that you can look up the tire specifications for different sizes on Tirerack. In order to do that you just have to look up the tire size by entering it manually. If you look it up by car, obviously, they will just tell you what the stock sizes are...

I'm saying tirerack doesn't give me any recommendations for a different size tire thats all...

[HerrK]

Originally Posted by dr_mikee

I'm saying tirerack doesn't give me any recommendations for a different size tire thats all...

There are no alternates or recommendations to stock BMW sizing - since BMW and hus TR only recommend RFT's and particular sizes of tire based on the wheel diameter.

You have to trailblaze if you so choose - that's what this particular thread is all about. You start with what is stock you write down the dimensions. You look around at brands of your choice. You check the dimensions. You compare the dimension to stock. You measure at your car. You read the forum - what people have tried, what works, what doesn't work. Then you decide - some independant thought process is required. There is some risk involved. Mitigate the risk.

Otherwise just stick with the stock sizes. Don't color outside the lines. Don't think outside the box.

[Vintage]

235/35-19 and 265/30-19

[Rafale]

Just finding out that the F10 has 245/35/19 paired with 275/30/19. I am wondering why BMW seem to always have slightly larger diameter front tires. The 225/35 with 255/30 also has the front to be a tiny bit taller but I thought it was due to limited choices.
235/35 with 275/30 are closer by far than the 245/35. or they should go 245/35 285/30. (that won't fit on the Z, it is too wide for the 9" wide wheels)

[VailM3]

whats the optimal PSI you should be running for non runflats. Swapping to the PSS the sidewall seems slightly "crushed" on the part the car is sitting on.

[ManiacGT]

Originally Posted by VailM3

whats the optimal PSI you should be running for non runflats. Swapping to the PSS the sidewall seems slightly "crushed" on the part the car is sitting on.

I'd be interested to know too. TBH that's what normal tyres look like though, we've just been used to the solid run flats!

[itf joegun]

Originally Posted by ManiacGT

I'd be interested to know too. TBH that's what normal tyres look like though, we've just been used to the solid run flats!

+1

[VailM3]

Originally Posted by ManiacGT

I'd be interested to know too. TBH that's what normal tyres look like though, we've just been used to the solid run flats!

yeah i guess I am used to how the sidewall doesnt compress between the ground and the rim. I saw my car last night (only drive once or twice a week) and though all my brand new tires were flat.

[mac-z4]

Does anyone have experience with or evaluated Michelin run flats; e.g Pilot Sport PS2 ZP or Primacy HP ZP ?

[Rafale]

Originally Posted by mac-z4

Does anyone have experience with or evaluated Michelin run flats; e.g Pilot Sport PS2 ZP or Primacy HP ZP ?

You probably won't find the Primacy in size suitable for the Z4. As for the PS2 ZP I have heard of good things about them but very limited. They improve over the OEM bridgestone RE050. Not sure how they compare to the non RFTs.

[wgreene9617]

Originally Posted by Rafale

ha! that was HerrK who has put the huge tires.
See the overall diameters

Front:
OEM 225/35x19 25.2"
HerrK's 235/40x19 26.4"
Mine 235/35x19 25.48"

Rear
OEM 255/30x19 25.02"
HerrK's 265/35x19 26.3"
Mine 275/30x19 25.5"

I went 0.2-0.5" wider diameter while HerrK went almost a whole 1.5"

I got my 235/35x19 fronts, 275/30x19 rears Michelin PSSs installed this morning. It is a cliche, but it is night and day difference. OMG the roads around town aren't that rough or loud after all.

[Rafale]

Originally Posted by wgreene9617

I got my 235/35x19 fronts, 275/30x19 rears Michelin PSSs installed this morning. It is a cliche, but it is night and day difference. OMG the roads around town aren't that rough or loud after all.

Don't you wonder why BMW used RFTs when the car is so much better behaved that way? A lot of negative reviews of the Z4 I am sure are coming from these damn tires...

[Asbjorn]

Originally Posted by Rafale

.... I am wondering why BMW seem to always have slightly larger diameter front tires. The 225/35 with 255/30 also has the front to be a tiny bit taller but I thought it was due to limited choices. ...

The second numbers 30 and 35 are not absolute heights but aspect ratios, ie a percentage of the absolute widths which are 225 and 255. So the actual heights are 78.7 and 76.6, front and rear. If both had been 30 the actual heights would have been 67.5 and 76.6, ie the total diameters would have been more more different.

And btw it is not always like this. The 1M and E9x M3 has 245 and 265 tires front and rear with same aspect ratios (always 40 for 18inch wheels and 35 for 19inch ones). The 2010 M3 GTS however had 255/35 and 285/30 tires on 19inch wheels.

[Rafale]

Originally Posted by Asbjorn

The second numbers 30 and 35 are not absolute heights but aspect ratios, ie a percentage of the absolute widths which are 225 and 255. So the actual heights are 78.7 and 76.6, front and rear. If both had been 30 the actual heights would have been 67.5 and 76.6, ie the total diameters would have been more more different.

And btw it is not always like this. The 1M and E9x M3 has 245 and 265 tires front and rear with same aspect ratios (always 40 for 18inch wheels and 35 for 19inch ones). The 2010 M3 GTS however had 255/35 and 285/30 tires on 19inch wheels.

I know it is a ratio and I took it into account and came to the same conclusion you did: The front are slightly taller than the rear.
M cars are different: Their chassis were design to not have a square setup. (there is no square setup option) whereas non M cars do.

[Asbjorn]

Originally Posted by Rafale

Don't you wonder why BMW used RFTs when the car is so much better behaved that way? A lot of negative reviews of the Z4 I am sure are coming from these damn tires...

+1 while they might be acceptable on the softer 1/3/5/etc-series with better sound isolation (and the brand's focus on family safety) the much more limited production Z4 should have been optimized to non-RFTs.

Fun fact: if you select 21" wheels, the X5 M is sold with RFTs sized 285/35R21 and 325/30R21.

[Asbjorn]

Originally Posted by Rafale

I know it is a ratio and I took it into account and came to the same conclusion you did: The front are slightly taller than the rear.
M cars are different: Their chassis were design to not have a square setup. (there is no square setup option) whereas non M cars do.

OK OK, then i think the answer is just that any other combination would generate a bigger total diameter difference between front and rear. It is simply impossible with the sizes available to get exactly the same diameter while running 225 & 255. Having a slightly bigger front is the best available option.

And btw regarding the 1M and M3, I have no idea why they decided to run a setup where the rears have a larger diameter than the fronts. The same is not the case with the M5 and M6 as far as I can see. And the previous M3 models were not configured like this either. They are also less staggered / more square than the Z4 and previous M3. Maybe they were trying to kill understeer?