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RFT Original Bridgestone fronts worn on both edges and changed at 17,000m. Loads of centre tread. Rears changed last Nov. Don’t tare ass.

Thinking is that they were under pressurised.

Going to get tracking checked...BTW, anyone know what’s best?

MOT next week.

Is this usual for a 340i MSport?
 

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RFT's are bad for wearing as if they're under-inflated. That's because the sidewalls can't stretch in the circumferential direction, like they can on a normal radial tire (tyre). Sidewall stretching lets the contact patch stay flat with the road. With diminished sidewall stretching in RFT's, the contact patch tends to buckle inward, concentrating the weight (and wear) around the edges of the contact patch. It's sort of like an uninflated soccer ball (football). There's no flat spot. Instead, there's a concave dimple.

My F10 535i came with Goodyear LS2 RFT's. The recommend pressures were 35 PSI front and 39 PSI rear. I had to run them at 42 PSI to get them to wear something close to evenly. That solved one problem, but created two more: horrible ride and horrible handling. In contrast, the non-RFT Michelin PSS's I put on wear evenly at 38 PSI front and 40 PSI rear. The ride and grip are a hell of a lot better, too.

Wear on both edges could also be caused by loose suspension parts, causing the tire to see both toe-in and toe-out. But, both-edge wear on both tires (tyres) on the same axle would suggest not enough pressure as the most likely cause.

I "dial in" the optimal pressures. I measure the tread depths in each channel when the tires are new. I guess at pressures, usually 5% to 10% over what the decal says measured in the mornings (coolest part of the day). I maintain those pressures for an entire rotation stint (~6k miles). I then measure the tread depths just before the next rotation. Based on the wear patterns, I adjust the pressure upward or downward for the next rotation stint. Checking the wear patterns also lets me see alignment problems early. I'll get 35k to 40k miles on the PSS's, even occasionally flicking the car around.

Your M Sport likely has a staggered set-up and can't rotate your tires (tyres) front to back. So, you're stuck with wearing out the rears faster than the fronts.

I've automated my tread depth data and wear calculations in an Excel spreadsheet. Here's three snapshots. The 45k mile data from my 535i shows over-inflation on the rear tires (excessive wear in the center (centre)). The 51k mile data from my 535i shows an alignment problem after hitting a pot hole a few k-miles earlier (excessive outer wear on three tires, slightly excessive inner wear on the fourth tire). The car still tracked straight, but there was a problem. The 117k mile data from my Chevy Cobalt shows excessive wear in the center (centre). But, that was intentional to even out the tread depths across the tires. I really flick the Cobalt around. Yet, the high-performance Conti' DW's will last over 40k miles. I could probably go to 50k miles and still not fail your MOT (1.6mm).

I call my process "tire whispering." It's sort of like horse whispering... except with tires instead of horses. I'm terrified of horses, and I stay away from them. :eek:
 

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RFT's are bad for wearing as if they're under-inflated. That's because the sidewalls can't stretch in the circumferential direction, like they can on a normal radial tire (tyre). Sidewall stretching lets the contact patch stay flat with the road. With diminished sidewall stretching in RFT's, the contact patch tends to buckle inward, concentrating the weight (and wear) around the edges of the contact patch. It's sort of like an uninflated soccer ball (football). There's no flat spot. Instead, there's a concave dimple.

My F10 535i came with Goodyear LS2 RFT's. The recommend pressures were 35 PSI front and 39 PSI rear. I had to run them at 42 PSI to get them to wear something close to evenly. That solved one problem, but created two more: horrible ride and horrible handling. In contrast, the non-RFT Michelin PSS's I put on wear evenly at 38 PSI front and 40 PSI rear. The ride and grip are a hell of a lot better, too.

Wear on both edges could also be caused by loose suspension parts, causing the tire to see both toe-in and toe-out. But, both-edge wear on both tires (tyres) on the same axle would suggest not enough pressure as the most likely cause.

I "dial in" the optimal pressures. I measure the tread depths in each channel when the tires are new. I guess at pressures, usually 5% to 10% over what the decal says measured in the mornings (coolest part of the day). I maintain those pressures for an entire rotation stint (~6k miles). I then measure the tread depths just before the next rotation. Based on the wear patterns, I adjust the pressure upward or downward for the next rotation stint. Checking the wear patterns also lets me see alignment problems early. I'll get 35k to 40k miles on the PSS's, even occasionally flicking the car around.

Your M Sport likely has a staggered set-up and can't rotate your tires (tyres) front to back. So, you're stuck with wearing out the rears faster than the fronts.

I've automated my tread depth data and wear calculations in an Excel spreadsheet. Here's three snapshots. The 45k mile data from my 535i shows over-inflation on the rear tires (excessive wear in the center (centre)). The 51k mile data from my 535i shows an alignment problem after hitting a pot hole a few k-miles earlier (excessive outer wear on three tires, slightly excessive inner wear on the fourth tire). The car still tracked straight, but there was a problem. The 117k mile data from my Chevy Cobalt shows excessive wear in the center (centre). But, that was intentional to even out the tread depths across the tires. I really flick the Cobalt around. Yet, the high-performance Conti' DW's will last over 40k miles. I could probably go to 50k miles and still not fail your MOT (1.6mm).

I call my process "tire whispering." It's sort of like horse whispering... except with tires instead of horses. I'm terrified of horses, and I stay away from them. :eek:


I know you are sick of hearing this stuff, but.... I have a 2017 440i Convertible and I have ONLY 13,000 miles on it (don't drive much). It is an automatic and I'd say 90% of miles are in the Comfort mode and 75% of the miles are NOT freeway miles. I religiously check air pressure in tires (according to placard on door & users manual, 36 front & 41 rear) once a week with a tire gauge and verify on cars pressure readout). The tires are original Pirelli RFT's, 225/40 R19 front and 255/35 R19 rear. The middle of tires (all 4) are just about bald while the edges look fine. I have never had a set of tires/car that have gone to hell in such a short mileage (even my C5 Corvette gave me an average of 32,000 miles and they were RFT's). Is pressure info on door placard/users manual wrong, are tires a bad lot, I am driving car just like I have driven all my other cars over the last 50 years, except not putting the mileage on since I've retired. Thanks


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Where do you get the idea that run flats are " bad for wearing as uf they are under inflated"? There are plenty of owners like me who get well over 50k miles on a set. I'm coming up on 70k miles.
 

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I know you are sick of hearing this stuff, but.... I have a 2017 440i Convertible and I have ONLY 13,000 miles on it (don't drive much). It is an automatic and I'd say 90% of miles are in the Comfort mode and 75% of the miles are NOT freeway miles. I religiously check air pressure in tires (according to placard on door & users manual, 36 front & 41 rear) once a week with a tire gauge and verify on cars pressure readout). The tires are original Pirelli RFT's, 225/40 R19 front and 255/35 R19 rear. The middle of tires (all 4) are just about bald while the edges look fine. I have never had a set of tires/car that have gone to hell in such a short mileage (even my C5 Corvette gave me an average of 32,000 miles and they were RFT's). Is pressure info on door placard/users manual wrong, are tires a bad lot, I am driving car just like I have driven all my other cars over the last 50 years, except not putting the mileage on since I've retired. Thanks


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I had the same problem with the rear (only) Michelin PS's (not PS2's or PSS's) on my E46 M3. I had the rear pressure down to 30 PSI, and they were still wearing more in the middle of the tire. I saw the same thing on a co-worker's Corvette. The air pressure causes the wider tires to bow out more in the center and therefore wear more in the center, sort of like walking across a 10' plank would cause it to bend more than a 6' plank under the same weight.

You're the first person I've heard complaining about excessive center wear on an RFT. It's usually excessive edge wear that's the problem with RFT's.

It sounds like you could benefit from practicing tire whispering, gradually lowering the pressure until wear is more even.

Isn't it great being retired? … and having time to do little things like checking your tire pressure every week.

I ran into an old boss in a restaurant Friday. He said "Happy Friday, Auto."

I said "Not for me. ... every day is Saturday."
 

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I had the same problem with the rear (only) Michelin PS's (not PS2's or PSS's) on my E46 M3. I had the rear pressure down to 30 PSI, and they were still wearing more in the middle of the tire. I saw the same thing on a co-worker's Corvette. The air pressure causes the wider tires to bow out more in the center and therefore wear more in the center, sort of like walking across a 10' plank would cause it to bend more than a 6' plank under the same weight.



You're the first person I've heard complaining about excessive center wear on an RFT. It's usually excessive edge wear that's the problem with RFT's.



It sounds like you could benefit from practicing tire whispering, gradually lowering the pressure until wear is more even.



Isn't it great being retired? … and having time to do little things like checking your tire pressure every week.



I ran into an old boss in a restaurant Friday. He said "Happy Friday, Auto."



I said "Not for me. ... every day is Saturday."


Thanks. Started reducing pressure yesterday by 2 psi all around, but I am afraid it is too late for these tires. The wear in the center is just too much. I do not know what to do, other than getting new tires (I do not believe the alignment has anything to do with what I am experiencing. Oh well, didn't really expect to have to get new tires after 13,100 miles. Haven't made up my mind whether I'll stick with RFT's (not Pirelli) or go to non RFT's. I went to non-RFT's for my last set of tires on my Corvette and was quite happy with them.

And yes, retirement is great. Once again, thanks,


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Where do you get the idea that run flats are " bad for wearing as uf they are under inflated"? There are plenty of owners like me who get well over 50k miles on a set. I'm coming up on 70k miles.
Like the OP, most people who complain about durability problems with RFT's have excessive wear on the edges, an exception being luckstr's 340i with Pirelli's.

Here were my tread depths at 31k miles, having had to grossly over-inflate the Goodyear LS2's to get them to wear evenly. I could have got 60k or 70k miles out of them. But, but it wasn't worth it because of the ride and handling.

My top-five records for mileage from a set of tires are: 79k miles (Honda Accord), 74k miles (Chevy Silverado 1500), 70k miles (VW Rabbit), 70k miles (VW Rabbit), and 68k miles (Nissan Sentra SE-R). But, these were all by taking the tires down to the wear bars (2/32nds inch of tread).
 

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Where do you get the idea that run flats are " bad for wearing as uf they are under inflated"? There are plenty of owners like me who get well over 50k miles on a set. I'm coming up on 70k miles.


I have gotten 35,000-45,000 on previous RFT's on my Corvette, so I was expecting something like that on my BMW. In your opinion, what do ai have to look for when I put new tires (all 4) on car so this does not happen to me again (replace at 13,000 mi)? Different tire pressure, alignment, etc.?
Thanks


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Discussion Starter #9
Great advice guys...thanks.

This morning I concluded the same and upped the pressures all round to 2.8 bar. I too think they were under inflated. Been upping the pressure since the original rears started showing wear on the edges.

Apols BTW for the English spelling. :)
 

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Before rotation comes inflation, but before inflation comes ALIGNMENT Alignment alignment.

ALIGNMENT, Alignment, alignment. Inflation. Rotation!
 

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Before rotation comes inflation, but before inflation comes ALIGNMENT Alignment alignment.

ALIGNMENT, Alignment, alignment. Inflation. Rotation!
That is a good one, will try to remember it. But, before ANY of that comes the moron behind the steering wheel. I just replaced all 4 all season tires on my grocery-getter (Golf GTI) @ barely over 20,000 miles. Evenly worn across, down to almost slicks. Service advisor could not believe the mileage.

And I have a different car to flog in a good season ... some people just cannot help themselves :D
 
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