Run Flat limits

[the_ulf]

surely, if safety is any concern at all, you wouldn't exceed the safe operating limits of a blown RFT by as much as 50%, irrespective of your in-depth knowledge of the vehicle. i wouldn't.



coincidentally, i don't actually see a problem with changing a wheel by the roadside. i did it before RFTs became a thing without incurring loss of limb or life.

[Tomaz]

[QUOTE=the_ulf; i don't actually see a problem with changing a wheel by the roadside. i did it before RFTs became a thing without incurring loss of limb or life.[/QUOTE]

I don't have a problem with changing a flat on the side of the road either. But my wife takes the car sometimes and I would rather she just drove home or to safety. In my area most of the travel is on superhighways so moving along with traffic is important and getting off an off ramp at night in some neighborhoods has its own risk. I would easily sacrifice a tire, a rim, or a major repair to get her home safely.

[the_ulf]

without wanting to turn this into an argument, i wasn't debating your or your wife's capabilities of changing a wheel, or the rationale behind preferring to drive home on a flat RFT. the thread is about the operating limits of RFTs and i'd most certainly question the wisdom in finding out just why exactly there's indeed a 50 mile/50mph limit while travelling at 75mph. you *might* get to your destination maybe 5 minutes sooner or maybe not at all. and is that really worth risking your vehicle?

[ard]

Originally Posted by trucky

Funny you should mention overheating as that was my first concern. Being an old truck driver with over a million miles crossing Donner Pass most days I take my tires and safety very seriously. One of my OCD habits during and after any trip is to actually feel the tires with the back of my hand and "taste" the temperature. While not an entirely scientific process it does allow me to know if one tire is significantly hotter than another. Running duals on truck and trailers it's not always visually apparent that one of your tires is low. The hand trick has saved me from adding to the tire carcasses along the road by discovering a hot tire and taking appropriate action.

I did the same with my X5 after arriving and found no discernible difference between the low RFT and the other 3 tires. I guess the proof will be to see if it survives as long as the other tires over time.

And why run on a RFT? Isn't that exactly the point of having RFTs? Having 3rd row seating there is no place to stow a spare. I was originally thinking about replacing the RFTs with non RFTs when they wore out but now I'm rethinking those thoughts.

Not trying to be adversarial at all Ard. I highly value your opinions on this and other BMW forums. Just sharing my personal perspective.

Good input.

While the point of having a RFT is to be able to drive on them, the question of "once driven on will this retain a safety rating" drives repair shops (and BMW) to declare 'no'. This protects them against the idiot that damages a tire, goes to a shop and an untrained tech pops a plug in a tire with a damaged carcass.


Personally havent seen enough internally damaged tires to know when they are toast- once I saw a tire with fine rubber 'shreads' coming off the interior. But in terms of looking at a puncture, feeling for delams, how to inspect the inner surface of the tire- I dunno.

I carry a spare, Id pull off the next exit or safe spot. My wife would do the same and call AAA. And Id have no qualms about repair of the tire in that scenario.

Finally I applaud the 'we will see how it fares' attitude. I cannot tell you how annoying the 'gotta pay to play' and 'are you willing to risk your FAMILY to save a few bucks" responses are.

PS Put that tire on the rear, just in case....

[trucky]

Just FYI: My flat was right rear, and there it stays. Had it been one of the front tires we would not be having this discussion.

I'm not a tire guy but I trust the place I go to and know the guys well. I watched as they spent a few minutes going over the entire tire in and out very carefully. They plugged then booted on a spreader machine. After booting they attached some sort of electrical tool to the booted area inside the tire and left it sit for about ten minutes. I don't know what this thing was but I'm guessing some sort of curing or annealing device. I don't know rubber compounds so I may not be using the right terms, but just saying it looked like they did a thorough job rather than a plug n run.

I'll be the first to return and report if that tire fails prematurely because I firmly believe we all learn from the shared experiences.

Finally, I want to be clear that I was neither condoning nor encouraging anyone to do as I did, I was merely sharing my own experience. I'm old, kind of onery, drive alone, and have driven through more rear blowouts and tire shreds than I want to remember over the years. If you've got a family in the car do the safe thing and follow the rules.

[Tomaz]

Originally Posted by trucky

Just FYI: My flat was right rear, and there it stays. Had it been one of the front tires we would not be having this discussion.

I'm not a tire guy but I trust the place I go to and know the guys well. I watched as they spent a few minutes going over the entire tire in and out very carefully. They plugged then booted on a spreader machine. After booting they attached some sort of electrical tool to the booted area inside the tire and left it sit for about ten minutes. I don't know what this thing was but I'm guessing some sort of curing or annealing device. I don't know rubber compounds so I may not be using the right terms, but just saying it looked like they did a thorough job rather than a plug n run.

I'll be the first to return and report if that tire fails prematurely because I firmly believe we all learn from the shared experiences.

Finally, I want to be clear that I was neither condoning nor encouraging anyone to do as I did, I was merely sharing my own experience. I'm old, kind of onery, drive alone, and have driven through more rear blowouts and tire shreds than I want to remember over the years. If you've got a family in the car do the safe thing and follow the rules.

I completely agree By the way, what was the size and manufacturer of the tire?

[trucky]

My tires are the BMW standard for that year, Bridgestone Dueler, 18 inch, about 12 k miles so far.

[Pat68]

really interesting this..
recently had a rear run flat go on my 4.6is with 20" standard wheels, i was in slow moving motorway traffic(30-40mph) and i only noticed when i could smell the burning rubber as the tyre was rubbing the inner wheel arch. i pulled over as soon as was safe and found a screw dead center of the tread. my car has LPG fitted so no spare !! i put 2 cans of aerosol emergency snot in and drove the last 6 miles home at around 25mph (side roads) stopping every 5 mins to check how hot the tyre had got, very. finally made it home and pulled the wheel off to find the inner wall of the tyre was almost completely worn away.
went to see my local tyre shop and asked him what he recommended as a replacement.. cheap Malaysian non run flat or bridgestone run flat. he explained the differences, and prices, and i decided to go with the cheap Malaysian as an experiment. these tyres are rated for the same speed as the expensive options and the fitter said he had fit loads of them with no come backs.
i am not a fast or sporty driver and here in the uk there are too many cameras to be anyway so why not. i will keep an eye on the wear and report back on here in a few thousand miles regarding wear/comfort/handling, if anyone is interested, but so far all is good.

ps, 2 cheap Malaysian tyres fitted and balanced were less than half the price of 1 Bridgestone !!!!!

Pat

[ard]

Originally Posted by Pat68

really interesting this..
recently had a rear run flat go on my 4.6is with 20" standard wheels, i was in slow moving motorway traffic(30-40mph) and i only noticed when i could smell the burning rubber as the tyre was rubbing the inner wheel arch. i pulled over as soon as was safe and found a screw dead center of the tread. my car has LPG fitted so no spare !! i put 2 cans of aerosol emergency snot in and drove the last 6 miles home at around 25mph (side roads) stopping every 5 mins to check how hot the tyre had got, very. finally made it home and pulled the wheel off to find the inner wall of the tyre was almost completely worn away.
went to see my local tyre shop and asked him what he recommended as a replacement.. cheap Malaysian non run flat or bridgestone run flat. he explained the differences, and prices, and i decided to go with the cheap Malaysian as an experiment. these tyres are rated for the same speed as the expensive options and the fitter said he had fit loads of them with no come backs.
i am not a fast or sporty driver and here in the uk there are too many cameras to be anyway so why not. i will keep an eye on the wear and report back on here in a few thousand miles regarding wear/comfort/handling, if anyone is interested, but so far all is good.

ps, 2 cheap Malaysian tyres fitted and balanced were less than half the price of 1 Bridgestone !!!!!

Pat

Only warning I can add is that you want to be sure the 'rolling diameter' is the same on the Malaysian tires as those on the other axle. Not just the numbers 3xx/xx-20, but the actual spec'd number.

[Tomaz]

ps, 2 cheap Malaysian tyres fitted and balanced were less than half the price of 1 Bridgestone !!!!!

Pat

What was the brand of those Malaysian tyres? Your tyres link didn't reveal. Just wondering. I am going to stick with Bridgstone when its time for a change.