Michelin PSS 19" Tire Size Question

[blschaefer1]

Hello,

I just swapped out my 135i for a Z4 35i with 19" wheels.

I plan on immediately swapping the run flats for PSS.

Any problems if I size up to 235/35 in the front and 265/30 in the rear?

On my 1'er, rub was always a concern but not sure how tricky these Z4's
are. I hear horror stories about cracked 296 style wheels and the slight extra height can't hurt either, I suppose.

Appreciate the advice.

[SCBMW02]

I have a 2011 35is with 19s. I ditched the run flats and put 235 35-19 on the front and 275 30-19 on the rear with no problems at all.

[Pacemaker1000]

^^^
sorry to hijack the thread but can you tell me what difference the PSS's made to ride quality? i find the 19's don't jar you but the ride is jittery and believe this is down to RFT's.

as far as sizing new tyres try this link to give you rolling sizes and wall heights etc
http://www.kouki.co.uk/utilities/vis...ize-calculator

interestingly, as i was contemplating downsizing to 18's for comfort, the difference in wall height is only 16.5% compared to 19's, so i don't know if that would be noticeable. certainly not as much as just changing to non-rft's and keeping the same wheel size

edit:
SCBMW02. I just worked out that with your rears you have increased the side by 6mm, and fronts by 3.5mm which is halfway between the gain made by 18's on the rear (12.75mm normal difference) and less than a third on the fronts (11.25mm normal) but probably messed up your speedo?

[blschaefer1]

Originally Posted by SCBMW02

I have a 2011 35is with 19s. I ditched the run flats and put 235 35-19 on the front and 275 30-19 on the rear with no problems at all.

Great to know, thanks. You running Pilot Super Sports? What wheels? The 296's are 19x8 front and 19x9 rear, which I just noticed is on the narrow end of the spec for this tire size.

From my experience with 18's on my 135i, the PSS's run a little wider than most tires for any given size. Just don't want any rubbing.

I have them ordered, should be here Tues.

[blschaefer1]

Originally Posted by Pacemaker1000

^^^
sorry to hijack the thread but can you tell me what difference the PSS's made to ride quality? i find the 19's don't jar you but the ride is jittery and believe this is down to RFT's.

as far as sizing new tyres try this link to give you rolling sizes and wall heights etc
http://www.kouki.co.uk/utilities/vis...ize-calculator

interestingly, as i was contemplating downsizing to 18's for comfort, the difference in wall height is only 16.5% compared to 19's, so i don't know if that would be noticeable. certainly not as much as just changing to non-rft's and keeping the same wheel size

edit:
SCBMW02. I just worked out that with your rears you have increased the side by 6mm, and fronts by 3.5mm which is halfway between the gain made by 18's on the rear (12.75mm normal difference) and less than a third on the fronts (11.25mm normal) but probably messed up your speedo?

I can only speak for my experience with my 1'er at this point, but the PSS tires really transformed the car. Much better ride quality and grip. Initial turn in might have been a bit more imprecise, but that could just be me. Can't wait to get them on the Z4. For the life of me I can't understand why BMW sees fit to handicap their higher performance cars with these things.

[Pacemaker1000]

cant wait to hear your opinion on ride comfort change on the Zed
speedo shouldn't be a problem as you have only gone up 3.5mm max which tread loss accommodates

[Seechun]

Just a question but without the RFTs what are you guys doing for a spare tyre solution? I'm looking at changing at some time but not sure about losing permanent boot space for a spare tyre

[Pacemaker1000]

A pump and some tyre weld an a can I assume

[blschaefer1]

Originally Posted by Seechun

Just a question but without the RFTs what are you guys doing for a spare tyre solution? I'm looking at changing at some time but not sure about losing permanent boot space for a spare tyre

I have this in the the trunk.

http://www.amazon.com/Slime-70005-Sa...=pd_sim_auto_1

[SCBMW02]

I bought the M mobility fix it kit that comes with M cars from BMW for $150

[nicknaz]

Originally Posted by blschaefer1

I have this in the the trunk.

http://www.amazon.com/Slime-70005-Sa...=pd_sim_auto_1

Hope you never have to use it... that stuff has let me down in the past!

Glad to see another Z owner from SD on the boards!

[blschaefer1]

Originally Posted by nicknaz

Hope you never have to use it... that stuff has let me down in the past!

Glad to see another Z owner from SD on the boards!

Thanks.

How does this kit differ from the BMW Mobility kit mentioned above?

[nicknaz]

Originally Posted by blschaefer1

Thanks.

How does this kit differ from the BMW Mobility kit mentioned above?

I don't know whether the chemistry of the kits is different but the general idea is that they inject a "goop" into the tire which is supposed to form a seal that holds air in when the "goop" gets hotter, and there is an air compressor incorporated that inflates the tire.

What ended up happening to me (1/4" nail puncture in the center of tread block, nail still embedded) is that the "goop" didn't actually form a seal and the air loss wasn't stopped at all. I had to overinflate the tire and cross fingers there was enough air to get to a tire shop.

I've also heard the "goop" ruins the TPMS but I have no first hand experience because this was on a non TPMS car.

EDIT: personally, I think the BMW kit is a rebrand of slime or some other similar product at a big mark up, and i wouldn't trust it. I don't have tech to back that up but that's my opinion and the reason i stick with RFT

[blschaefer1]

Originally Posted by nicknaz

I don't know whether the chemistry of the kits is different but the general idea is that they inject a "goop" into the tire which is supposed to form a seal that holds air in when the "goop" gets hotter, and there is an air compressor incorporated that inflates the tire.

What ended up happening to me (1/4" nail puncture in the center of tread block, nail still embedded) is that the "goop" didn't actually form a seal and the air loss wasn't stopped at all. I had to overinflate the tire and cross fingers there was enough air to get to a tire shop.

I've also heard the "goop" ruins the TPMS but I have no first hand experience because this was on a non TPMS car.

EDIT: personally, I think the BMW kit is a rebrand of slime or some other similar product at a big mark up, and i wouldn't trust it. I don't have tech to back that up but that's my opinion and the reason i stick with RFT

That BMW Mobility kit is the same one that they put in all of the M cars. Interesting that they don't fit RFT's on the M cars, that tells you something. I figure if its good enough for the M cars its good enough for me, but agree, hope I never need to use it.

Anyway, I got the PSS's installed the other day. They are great, the increased grip is amazing, ride nominally smoother. They seem to have slightly higher road noise, which is opposite of my experience with them in my 135i. I have not fooled around with pressures yet, but will.

No fit issues with the 235/35/19 fronts and 265/30/19 rears. They fill in the wheel wells a little better too.

[Pacemaker1000]

Originally Posted by blschaefer1

That BMW Mobility kit is the same one that they put in all of the M cars. Interesting that they don't fit RFT's on the M cars, that tells you something. I figure if its good enough for the M cars its good enough for me, but agree, hope I never need to use it.

Anyway, I got the PSS's installed the other day. They are great, the increased grip is amazing, ride nominally smoother. They seem to have slightly higher road noise, which is opposite of my experience with them in my 135i. I have not fooled around with pressures yet, but will.

No fit issues with the 235/35/19 fronts and 265/30/19 rears. They fill in the wheel wells a little better too.

Shame the ride is not a big difference
What about he speedo? Any change? And if so is it a higher or lower reading?

[blschaefer1]

Originally Posted by Pacemaker1000

Shame the ride is not a big difference
What about he speedo? Any change? And if so is it a higher or lower reading?

Don't get me wrong, the ride is clearly smoother.

Not sure about the speedo, I'll need to check. As the diameter is slightly larger, it may be a little low. In my experience, BMW calibrates the speedos on the high side anyway, so it may actually be MORE accutate than before.

[Pacemaker1000]

Originally Posted by blschaefer1

Don't get me wrong, the ride is clearly smoother.

Not sure about the speedo, I'll need to check. As the diameter is slightly larger, it may be a little low. In my experience, BMW calibrates the speedos on the high side anyway, so it may actually be MORE accutate than before.

My speedo is already slow by about 3 mph

[nicknaz]

Originally Posted by blschaefer1

Anyway, I got the PSS's installed the other day. They are great, the increased grip is amazing, ride nominally smoother. They seem to have slightly higher road noise, which is opposite of my experience with them in my 135i. I have not fooled around with pressures yet, but will.

Do you have any lap times or other data on the stockers vs. PSS? I'm on the fence due to lack of spare and haven't been able to find data on the change. "feel" can be misleading sometimes and I need some tech to convince me to take on the the risk of needing a flatbed to get home.

[blschaefer1]

Originally Posted by nicknaz

Do you have any lap times or other data on the stockers vs. PSS? I'm on the fence due to lack of spare and haven't been able to find data on the change. "feel" can be misleading sometimes and I need some tech to convince me to take on the the risk of needing a flatbed to get home.

No hard data. I don't track my car. Do some searches on these tires, and I think you will find others echo my comments. The car clearly has more grip than with the rft's, and the lack of super stiff sidewalls help smooth out the ride. Its quite obvious if you were to drive them back to back. No sure about the flatbed issue, I think the mobility kit will me get to a shop if needed.

[Pacemaker1000]

speedo readings please?

in UK ALL Minis without RFT's come with a pump and sealer. Maybe worth checking what they use?

edit:
http://www.realoem.com/bmw/showparts...=71&fg=95&hl=1

[z4z4z4]

Originally Posted by Pacemaker1000

speedo readings please?


]

You can lookup the diameter of various size and make of tires to determine the variable to plug into the formula. Diameters vary by tire manufacturers for the same sizes. It's not an exact science as temps and pressure are variables to acknowledge.
I used the PSS 19" diameter for 265-30 for the following graphic of a spreadsheet.

[wdlfbio]

Originally Posted by Pacemaker1000

My speedo is already slow by about 3 mph

All our analog speedos over rate by 6%. It's been shown over and over. But, there is a fix.

Coding:
It is pretty easy to have someone activate the digital velocity indicator in the car and then tell the car to show the actual mph. The analog gauge will read high, but your digital will be right on. There are Indy shops that'll do this as well as a few guys remotely. Check out the E90 page-coding forum and you'll find all kinds of other cool things you can turn on for our cars.