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[jarviscochrane]

I just picked up a used set of OEM M68 rims for winter wheels on my 135i.

They came with Blizzak LM-25's on the rear with 90%+ tread remaining, and Blizzak MZ-01's on the front which need replacing. 225/45/17 all around.

I was about to order 2x LM-25's for the front from Tirerack to make a matched set, but realized that the LM-25's I have mounted on the rear do not indicate anywhere that they are Run Flats.

Does anyone know if Bridgestone offered a non-RFT version of the LM-25? Or are they all RFT? I can't find the "RSC" circle anywhere.

And lastly, if I buy RFT LM-25's for the front, will the M68 rim accept the RFT tire? If not I'll just swap all 4 out for non-rft dunlops and ditch 2 perfectly good LM-25s.

[Lester]

These are not Run FLat's.

Here is what Tirerack.com says on these:

The Blizzak LM-25 is Bridgestone's Performance Winter tire developed for the drivers of high performance sports cars, sport coupes and sport sedans that require winter driving traction on dry, wet and snow-covered roads. Blizzak LM-25 winter tires are designed to combine good snow and ice traction with "European" high-speed winter driving performance.

The Blizzak LM-25 winter tire's overall combination of capabilities is made possible by Bridgestone's UNI-T technology that brings advanced tire technologies together. Innovative tire design, construction and tread compound help maximize the tire's performance, ride quality and wear while providing traction in winter.

Blizzak LM-25 winter tires feature a directional tread design with rounded tread shoulders to increase hydroplaning resistance on wet and slush-covered roads while enhancing dry and wet road handling. They use a high silica content winter tread compound to combine winter traction with high-speed durability (the current Multicell tread compounds used on most Blizzak winter tires cannot support H- or V-speed ratings). The Blizzak LM-25 features an independent block tread design that employs the Lamellen "edge effect" with multiple three dimensional ("3D") zigzag sipes specifically placed in the tread blocks to provide the biting edges needed to help grip snow and ice for winter traction without resorting to traditional metal studs.

Blizzak LM-25 winter tires meet the industry's severe snow service requirements and are branded with the snowflake-on-the-mountain symbol.

Install Blizzak LM-25 tires in sets of four only.

Due to the traction capabilities of the Blizzak LM-25, Bridgestone recommends using Blizzak LM-25 tires only in sets of four to provide the best handling characteristics and tire performance.

[MarkR171]

Quick answer: no. RFT can go on any wheel.

[aerobod]

Originally Posted by MarkR171

Quick answer: no. RFT can go on any wheel.

RFTs can't be fitted to any wheel, they require a wheel marked with EH2 or EH2+ (enhanced double hump). Without the larger hump, the RFT tyre bead will come off the rim with no air pressure, leaving you stranded in the same way a non-RFT will.

[jarviscochrane]

These rims are marked eh2 so I should be good.

The only lm-25 tirerack shows on product search is indicated as runflat - there is not a non runflat option.

So was rft added to the lm-25 after it's initial release?

[MarkR171]

Originally Posted by aerobod

RFTs can't be fitted to any wheel, they require a wheel marked with EH2 or EH2+ (enhanced double hump). Without the larger hump, the RFT tyre bead will come off the rim with no air pressure, leaving you stranded in the same way a non-RFT will.

I stand corrected.

[Lubo]

Originally Posted by jarviscochrane

These rims are marked eh2 so I should be good.

The only lm-25 tirerack shows on product search is indicated as runflat - there is not a non runflat option.

So was rft added to the lm-25 after it's initial release?

LM25 was an old model. New model I believe is LM60. Probably there is not LM60 RFT yet so Tire Rack is still selling the old LM25 RFT.

[boostm3]

Originally Posted by aerobod

RFTs can't be fitted to any wheel, they require a wheel marked with EH2 or EH2+ (enhanced double hump). Without the larger hump, the RFT tyre bead will come off the rim with no air pressure, leaving you stranded in the same way a non-RFT will.

Not according to Gil at Tirerack whom I just called about this is relative to my recent delivery of Elbrus 102 rims and Pirelli Sottozero Winter 210 Rfts.. He told me that while the bmw stock rims are so marked, most or all of the tirerack rims are not, and the runflats work fine with the rims they sell and theres no danger of the bead coming off the wheel when the tire has no air.. Thats pretty much verbatim.

[aerobod]

Originally Posted by boostm3

Not according to Gil at Tirerack whom I just called about this is relative to my recent delivery of Elbrus 102 rims and Pirelli Sottozero Winter 210 Rfts.. He told me that while the bmw stock rims are so marked, most or all of the tirerack rims are not, and the runflats work fine with the rims they sell and theres no danger of the bead coming off the wheel when the tire has no air.. Thats pretty much verbatim.

There are aftermarket rims that meet the EH2 or EH2+ specification, if it isn't marked on the wheel, it should be in the specifications from the manufacturer. The EH2 hump was moved inward and is a little higher than a conventional hump to retain the bead of an RFT tyre. Here is a document that explains some of the differences, read page 16 about the differences between a standard (H or H2) rim and an EH2 rim: http://www.wdk.de/index.php?download...e_changers.pdf

You can put RFTs on a conventional rim, but the bead is not likely to stay on with zero pressure, so why use an RFT when it won't function as one?

[boostm3]

Originally Posted by aerobod

There are aftermarket rims that meet the EH2 or EH2+ specification, if it isn't marked on the wheel, it should be in the specifications from the manufacturer. The EH2 hump was moved inward and is a little higher than a conventional hump to retain the bead of an RFT tyre. Here is a document that explains some of the differences, read page 16 about the differences between a standard (H or H2) rim and an EH2 rim: http://www.wdk.de/index.php?download...e_changers.pdf

You can put RFTs on a conventional rim, but the bead is not likely to stay on with zero pressure, so why use an RFT when it won't function as one?

Again, while bmw rims are so marked, Gil at Tirerack says runflats will run fine on rims not carrying the EH2 spec, and function as they should. Most techs at Tirerack apparently havent even heard of this spec! I determined this by making 2 calls and questioning the reps, neither of which were familiar. Gil who supports this forum and IS familiar with the spec, on the other hand, said its not necessary for proper functioning.. Most if not all the wheels sold by Tirerack do not carry this spec. So, seems to me the question would be, why does Tirerack sell runflat tires installed on rims not carrying the EH2 (or any variation thereof) designation? I would assume if there were a repeatable bead issue that occurred as a result of mounting runflats on non EH2 spec rims, tirerack would have some legal culpability for selling and mounting tires on wheels they do not belong on should it ever reach a court of law after a malfunction occurred as a result. And if this ever happened, one can only assume theyd stop selling 'mismatched' tires wrt eh2 rims. So far, this doesnt seem to be the case.

Im not saying you are wrong; only that, perhaps, this is an 'ideal type' spec that in reality doesnt necessarily require strict adherance. Sometimes, its very difficult to determine how much is science, and how much is marketing. I would really hate to think Tirerack is creating unsafe situations by purposely ignoring a spec which is absolutely mandatory for proper functioning of the products they sell. Tirerack has always performed well for me, so while I believe it would probably be better to use EH2 rims, I also believe its not mandatory for proper functioning of runflat tires. Sure hope Im not the one to prove this wrong!

[aerobod]

Originally Posted by boostm3

Again, while bmw rims are so marked, Gil at Tirerack says runflats will run fine on rims not carrying the EH2 spec, and function as they should. Most techs at Tirerack apparently havent even heard of this spec! I determined this by making 2 calls and questioning the reps, neither of which were familiar. Gil who supports this forum and IS familiar with the spec, on the other hand, said its not necessary for proper functioning.. Most if not all the wheels sold by Tirerack do not carry this spec. So, seems to me the question would be, why does Tirerack sell runflat tires installed on rims not carrying the EH2 (or any variation thereof) designation? I would assume if there were a repeatable bead issue that occurred as a result of mounting runflats on none EH2 spec rims, tirerack would have some legal culpability for selling and mounting tires on wheels they do not belong on should it ever reach a court of law after a malfunction occurred as a result. And if this ever happened, one can only assume theyd stop selling 'mismatched' tires wrt eh2 rims. So far, this doesnt seem to be the case.

Im not saying you are wrong; only that, perhaps, this is an 'ideal type' spec that in reality doesnt necessarily require strict adherance. Sometimes, its very difficult to determine how much is science, and how much is marketing. I would really hate to think Tirerack is culpable for creating unsafe situations by purposely ignoring a spec which is absolutely mandatory for proper functioning of the products they sell.

Although I have the greatest respect for TireRack as a tyre retailer, the engineers from the tyre and car manufacturers designed the current generation of runflats to be used with EH2 rims. This is Pirelli's position: "Is it possible to fit a self-supporting run flat tyre on standard H2 rims? If so, will it still work as a run flat tyre and what are the implications?
Yes it is possible, although Pirelli strongly recommend that EH2 rims are used because they guarantee improved retention of the tyre bead down to zero inflation pressure." from the Pirelli FAQ at http://www.pirelli.co.uk/web/technol...q/default.page