Why I ditched the run-flat tires on my new Z4

Run-flat tires (RFTs) sound like a good idea in theory, in that you do not have to carry a spare tire or change a tire by the side of the road. However, in practice, they have several disadvantages that override their single advantage:
1. RFTs give a harsh ride and tiresome road noise. And that is something you tolerate every day you drive.
2. RFTs cost 50% more than conventional tires and last half as long.
3. RFTs cannot be repaired if you get a puncture, so a simple puncture costs you a new tire.

Conventional tires have all the advantages. They provide a smoother and less harsh sounding ride, and a puncture can be repaired for minimal cost. So what do you do when you get a flat tire? Serious road damage to a tire means the car must be towed, but that is also true with run-flat tires, unless you carry a spare. If you get a tire puncture there are several options, listed here in order of preferred action:
1. Since 80% of punctures are slow leaks, the tire pressure sensor should alert you to the problem in time to get to a garage.
2. If you carry a 12V electric pump and you can top up the pressure enough to get to a garage.
3. You can get the car towed. Join AAA and get towing coverage.
4. If you carry a jack and lug wrench, you could remove the wheel and take it to a garage. If you discover the leak in the morning at home and you have a second car, you can have it repaired with minimal trouble and cost.
5. As a worst-case scenario, if you carry a pump and tire plug kit, you can plug the leak and pump up the tire. Fast leaks are easy to find and the repair takes less time than changing a tire. This means you will have ruined the tire in that it cannot then be repaired properly, but you can get home. Just like in the case of having a run-flat tire, you will need to purchase a new tire, but the cost will be 50% less and a conventional tire replacement will be easier to find. Plus, RFTs only give you 50 miles without air, while a plugged tire can be good for hundreds of miles. It used to be the way most garages repaired a puncture.
Here are photos of my new car:
https://picasaweb.google.com/1151189...9572/BMWZ435is

Originally Posted by KAJ

Run-flat tires (RFTs) sound like a good idea in theory, in that you do not have to carry a spare tire or change a tire by the side of the road. However, in practice, they have several disadvantages that override their single advantage:
1. RFTs give a harsh ride and tiresome road noise. And that is something you tolerate everyday you drive.
2. RFTs cost 50% more than conventional tires and last half as long.
3. RFTs cannot be repaired if you get a puncture, so a simple puncture costs you a new tire.

1. It depends on the tire. Not all RFTs are the same.
2. Agree about price - but not treadwear. IIRC, your Bridgestone Potenzas have a 140 UTQG rating, but RFTs are available with higher ratings. The Bridgestone Turanzas (300 UTQG) on my E91 are less than half worn at 25,000 miles, for example.
3. Nonsense. As long as the tire has not been damaged by running it while totally flat, punctures may be repaired like any other tire. This is the reason I carry a 12v. compressor, even with RFTs and the one puncture repair I've had has held up just fine for the past 4,000 miles.

So it really comes down to a personal decision as to whether the price difference is worth the RFT convenience.

Tom

Originally Posted by KAJ

1. Since 80% of punctures are slow leaks, the tire pressure sensor should alert you to the problem in time to get to a garage.
2. If you carry a 12V electric pump and you can top up the pressure enough to get to a garage.

1. Please cite your reference for this data. (Edit: reference below.)

2. Not if the puncture is in the sidewall.

Here is the source. http://www.edmunds.com/driving-tips/...-a-primer.html

Actually the Edmonds article says 85% of flats are slow leaks and they point to the importance of tire pressure sensors in alerting you to a leak before the tire is flat.

It is good that you asked for a source for this information since too much on forums, in general, and on the topic of run-flat tires, in particular, is just opinion or anecdotal information.

In terms of side punctures, sure there is no repair in any case. But the only sidewall puncture I have had in 30 years of driving was a slow leak, so a 12v pump could have helped. I was camping in Texas and got a cactus thorn.

On the issue of repairability of run-flat tires, my source is the manager of the local Firestone store. He said that they are not allowed to repair run-flats, but that other garages will do the repair. Obviously, Firestone has reasons for banning repairs. It would be interesting to hear from other members of this forum on whether they could get run-flat tires repaired and what their experience was afterwards.

By the way, nice car and interesting photos! I almost purchased that color, but then decided I just had to have red.
https://picasaweb.google.com/1151189...9572/BMWZ435is
2013 BMW Z4 35is, Melbourne Red Metallic on Beige Kansas leather, 18 inch wheels, Navigation, backup sensor.

Originally Posted by SD Z4MR

1. Please cite your reference for this data. Or did you just make up "80%"? Arguments mean nothing if you just make up irrelevant data points. If you can cite some authoritative source that supports this, I will retract this post. Otherwise you're just blowin' smoke out of your ...

2. Not if the puncture is in the sidewall.

I extracted the text so you can "retract your post". And a sidewall issue will take out run flats as well.


Ironically, TPMS makes the case for run-flats less compelling. Since these systems excel at alerting drivers to underinflation and slow leaks before they can fester and weaken a tire, the likelihood of certain types of blowouts and flat tires is reduced. In making the case for mandatory TPMS, the NHTSA cited tire industry data claiming that 85 percent of tire deflations are slow leaks — some of which go unnoticed and end up as blowouts. The remaining 15 percent are due to sudden ruptures or large punctures. Other industry sources put the sudden rupture percentage even lower than 15 percent.

Originally Posted by KAJ

Run-flat tires (RFTs) sound like a good idea in theory, in that you do not have to carry a spare tire or change a tire by the side of the road. However, in practice, they have several disadvantages that override their single advantage:
1. RFTs give a harsh ride and tiresome road noise. And that is something you tolerate everyday you drive.
2. RFTs cost 50% more than conventional tires and last half as long.
3. RFTs cannot be repaired if you get a puncture, so a simple puncture costs you a new tire.

Conventional tires have all the advantages. They provide a smoother and less harsh sounding ride, and a puncture can be repaired for minimal cost. So what do you do when you get a flat tire? Serious road damage to a tire means the car must be towed, but that is also true with run-flat tires, unless you carry a spare. If you get a tire puncture there are several options, listed here in order of preferred action:
1. Since 80% of punctures are slow leaks, the tire pressure sensor should alert you to the problem in time to get to a garage.
2. If you carry a 12V electric pump and you can top up the pressure enough to get to a garage.
3. You can get the car towed. Join AAA and get towing coverage.
4. If you carry a jack and lug wrench, you could remove the wheel and take it to a garage. If you discover the leak in the morning at home and you have a second car, you can have it repaired with minimal trouble and cost.
5. As a worst-case scenario, if you carry a pump and tire plug kit, you can plug the leak and pump up the tire. Fast leaks are easy to find and the repair takes less time than changing a tire. This means you will have ruined the tire in that it cannot then be repaired properly, but you can get home. Just like in the case of having a run-flat tire, you will need to purchase a new tire, but the cost will be 50% less and a conventional tire replacement will be easier to find. Plus, RFTs only give you 50 miles without air, while a plugged tire can be good for hundreds of miles. It used to be the way most garages repaired a puncture.

You can go a step further and carry a device like this:

http://www.slime.com/shop/safety-spair-70005/

My experience with run flats was that they lasted just as long as any other performance tire but did not seem to wear evenly. I had two sets of run flats, Conti and Bridgstone, and both tended to vibrate and make noise after 20K miles or so even after having them balanced. Once I changed to non run flats I have not had this problem.

I asked the manager of the Firestone store about Slime and he recommended against its use. I used a tire-fix compressed-air goop once to plug a slow leak. The garage in a small town in west Texas that did the subsequent repair only plugged the tire and did not take the tire off to clean out the goop. A year later the tire developed a large bulge which was blamed on the tire-fix goop. It was a different brand than Slime, but it makes sense that the slime would need to be washed out of the tire when it was repaired properly. Perhaps that is why the Firestone dealer dislikes Slime. Although I would avoid using Slime, I agree that it could get you home if all else fails.

Originally Posted by KAJ

I asked the manager of the Firestone store about Slime and he recommended against its use. I used a tire-fix compressed-air goop once to plug a slow leak. The garage in a small town in west Texas that did the subsequent repair only plugged the tire and did not take the tire off to clean out the goop. A year later the tire developed a large bulge which was blamed on the tire-fix goop. It was a different brand than Slime, but it makes sense that the slime would need to be washed out of the tire when it was repaired properly. Perhaps that is why the Firestone dealer dislikes Slime. Although I would avoid using Slime, I agree that it could get you home if all else fails.

Sounds to me like you have constant tire problems for one reason or another whether it be RF or other tires.
Good luck
cheers
vern

Vern, Actually no. I have had only 3 flat tires that I remember in 40 years of driving. That is one reason why I don't think run-flat tires are such a necessity.
By the way, nice photo! Ken


2013 BMW Z4 35is, Melbourne Red Metallic on Beige Kansas leather, 18 inch wheels, Navigation, backup sensor.

Originally Posted by KAJ

Here is the source. http://www.edmunds.com/driving-tips/...-a-primer.html

Actually the Edmonds article says 85% of flats are slow leaks and they point to the importance of tire pressure sensors in alerting you to a leak before the tire is flat.

It is good that you asked for a source for this information since too much on forums, in general, and on the topic of run-flat tires, in particular, is just opinion or anecdotal information.

In terms of side punctures, sure there is no repair in any case. But the only sidewall puncture I have had in 30 years of driving was a slow leak, so a 12v pump could have helped. I was camping in Texas and got a cactus thorn.

On the issue of repairability of run-flat tires, my source is the manager of the local Firestone store. He said that they are not allowed to repair run-flats, but that other garages will do the repair. Obviously, Firestone has reasons for banning repairs. It would be interesting to hear from other members of this forum on whether they could get run-flat tires repaired and what their experience was afterwards.

By the way, nice car and interesting photos! I almost purchased that color, but then decided I just had to have red.
https://picasaweb.google.com/1151189...9572/BMWZ435is
2013 BMW Z4 35is, Melbourne Red Metallic on Beige Kansas leather, 18 inch wheels, Navigation, backup sensor.

Fair enough! Thanks for posting the source and I have edited my original post. I agree with your statement about forum information in general, so citing your source is appreciated. Because of this I always try to find a credible source for any info I post if I think it's necessary.

We had a puncture in the right rear run flat tire on our 335is during our European Delivery. Germany doesn't allow punctures to be repaired so the BMW service center found a new tire. The charge for our new tire, including mounting and balancing, showed up on our credit car statement as $580 which also included 19% German VAT.

Your E89 Z4 35is is the spiritual successor to my E85 Z4 M Roadster since unfortunately, BMW has not decided not to grace the E89 Z4 with a ///M badge. If I were to order this model the Melbourne Red would be my choice since there is no exclusive "M" blue to choose from. My previous car was a 2000 S2000 and I really wanted the New Formula Red, but the only color the dealer had left when my number came up on the waiting list was Silverstone Metallic. Fortunately, it was a very nice, dark silver. I only had 2 flat tires with that car in 13 years, both were one of the rear tires, but it had a compact spare.

Since the Z4 M Roadster and Coupes came with non-runflat tires BMW's solution was the M Mobility Kit, a 12V compressor with a can of tire sealant. I've added a tire plug kit, but my primary solution will be roadside service with my legacy AAA membership, Liberty Mutual insurance, or BMW Assist.

Latest rft are very good if normal tyres are 10 then latest rft are 8

Troll or hijack? Maybe.
Since the OEM Conti Sports left me a long time ago, I use either Kumho or Yokohama "real" tires on my '01 330i 5 spd SP (ODO 144K miles). I feel so comfortable with them I have not carried a spare in years. Tire problems (except for slow leaks from nails) have never been a concerning subject to me.