Run Flat tires vs Normal tires - dealer cut away carcuss...

[Vintage]

I like RFTs too and thanks for the pictures. Nothing beats a non-RFT for pure performance but I like knowing my wife is driving around on a RFT.

[BrokenVert]

Agreed with captainaudio I've had to drive on 2nd ave on both rfts and non rfts (my sis lives on the upper east side) and the ride on the nonrfts was amazingly better

[Northx]

Originally Posted by zoom335is

I like that BMW got rid of the spare, no wasted space, no extra tire changing gear, less weight, I approve. In the 10 years I have been driving I have gotten maybe 4 flat tires, not bad. I have not experience enough flat tired to need the RTF's or even a spare. Even if I do, I just use BMW services, get my car taken to a dealer, replace tire, on my way. My 335is came with summer "sport" RTF's but will not replace them until they are worn, but I will grab non RTF winter tires and when time comes non RTF summer tires.

Found this on wikipedia:
"Self-supporting run flat tires typically carry a 15% - 27% weight penalty over similar standard tires, or additional 2-3 kg (4-7 lb).[citation needed] The additional mass concentrated on the outer edge of the wheels can impose a significant performance penalty due to greater rotational and unsprung mass."

Not a big weight savings to pull out a 20lb tire but add 5lb to each of the four on the car. Interesting read on unsprung mass re the CTO effect that captainaudio was talking about.

[bobbyd1961]

Originally Posted by Dackelone

Thanks for pointing that out! I corrected it. The RFT are on the right side in my photos. You can tell a RFT bc the side wall and thread surface is so much thicker than a normal tire. The RFT also have very little "flex" in it vs a normal tire.

the runflats on my 335 were so hard and stiff that when i hit the smallest bump the front end felt like it was going to fall off. id actually cringe before hitting bumps that couldnt be avoided.

[TimE90]

Originally Posted by ptack

It's why we call them run craps.

+1

[Dackelone]

Speaking of tire weight... I heard that for guys who want the MAX ACELL times... like when at the drags... going to a regular tire in 17" size, will give the car better acell times!?!? Slightly shorter wheel with less total mass.

Btw... I have said this before... I have found that my run flat tires are VERY sensitive to tire pressure. What I mean is just a few psi more and they will really ride like crap. Lower the psi and they ride fairly nice. just FYI.

[ptack]

Originally Posted by michifan

I'm a fan of run flats as well. They are safer and weigh less (including spare delete). The ride is firm, but I'm kinda used to that kind of ride.

Personally, I'd be willing to bet that 90% of the people that think they hate them wouldn't know the difference on regular roads without knowing that they were running run flats vs regular tires.

Nobody argues that run flats make bad track tires, but most guys I know have track specific tires anyway.

Let's just say that if you can't tell the difference you're probably not that much into driving the car seriously anyway. That may be fine for the average schlub, but on this forum it's the other way around.

[captainaudio]

Originally Posted by Dackelone

Speaking of tire weight... I heard that for guys who want the MAX ACELL times... like when at the drags... going to a regular tire in 17" size, will give the car better acell times!?!? Slightly shorter wheel with less total mass.

Btw... I have said this before... I have found that my run flat tires are VERY sensitive to tire pressure. What I mean is just a few psi more and they will really ride like crap. Lower the psi and they ride fairly nice. just FYI.

I discovered, purely by accident, that my non RFTs (Pirelli P_Zero Nero M&S) actually had better ride quality when I INCREASED the tire pressure to about 4PSI over the recommended pressure. At first I thought I was imagining it but Ms. Audio noticed the same thing. I know this is totally counter-intuitive but I have mentioned this to other BMW drivers who have noticed the same thing. My car is a 335i E93 with sport suspension.

CA

[Red Bread]

Originally Posted by maxnix

I like my wife driving around with towing insurance and AAA on non-RFT.

Ding! My preferred solution too. My M Coupe has made it a decade without a spare, and without those silly tires. One blowout, a 160 mile tow and two new rear tires is the only downside. Total time lost, about an hour. I think if I buy another car that comes with runflats, I won't wait to burn them off, I'll just replace them up front.

[BrokenVert]

Originally Posted by Red Bread

Ding! My preferred solution too. My M Coupe has made it a decade without a spare, and without those silly tires. One blowout, a 160 mile tow and two new rear tires is the only downside. Total time lost, about an hour. I think if I buy another car that comes with runflats, I won't wait to burn them off, I'll just replace them up front.

The only time that I've ever had a flat was from a blown sidewall on a runflat.

I've got two cans of fix a flat and I haven't had to use them for two years

[ianc]

What is BMW's stance on roadside assistance if you call with a flat Hankook...

ianc

[captainaudio]

Originally Posted by ianc

What is BMW's stance on roadside assistance if you call with a flat Hankook...

ianc

I just went through that with BMW Assist and a blown Pirelli. BMW Assist will tow you to the dealer regardless of what tire is on the car. Actually when they dispatch the tow truck they have no idea what tires are on the car. The tow truck operators are sub-contractors and could not care less what kind of tires are on the car.

CA

[ianc]

BMW Assist will tow you to the dealer...

Only to the dealer? Supposed you wanted to go to the tire shop of your choice, for example?

ianc

[Dackelone]

Does BMW NA have guys who drive around to help you like this? They are techs who come to help repair your car on teh side of the road. Much like the ADAC but they work for BMW AG. I was just wondering IF BMW NA had teh same program?

[ianc]

Nothing like that here David; that's why we get free maintenance!

ianc

[captainaudio]

Originally Posted by Zell

Though they make a harsher ride, I think the added safety of them is very nice.

I don't buy into the fact that they are safer, primarily because of their inability to stay in contact with the surface of bumpy roads. Perhaps safer in some respects but IMPO more dangerous in others.

A

[cotmfk]

Boo runflats. Heavy. Harsh. Expensive.

[ptack]

Ask yourself why BMW doesn't put run craps on the M3? It's because they suck as high performance tires. If you drive a 135i anything like an M3, you will notice.

[hotrod182]

On the rare occassions I put on my stock 18" RFTs, I thought the heavier tires and wheels actually rode smoother. Racing through the canyons, and instrumenting my 60' times, I actually was pretty impressed by the RFTs. I wouldn't mind running them most of the time if they weren't so expensive, considering I usually only get about 7000 miles on a set of rear tires. But for track performance, etc, one of the main things I can't overlook is the weight penalty of the RFTs. But other than that, I'm pretty impressed by their performance.

[bozola]

My RFTs are shot and I have new Mich Pilot A/S in the garage. Needless to say.. I am very curious to feel the difference.

[kaishang]

Everyone who things runflats are harsh riding:

- Do you have the M-sport suspension or the standard suspension?
- What size tyres are you running?

[Pol]

Originally Posted by Dackelone

Does BMW NA have guys who drive around to help you like this? They are techs who come to help repair your car on teh side of the road. Much like the ADAC but they work for BMW AG. I was just wondering IF BMW NA had teh same program?

Here in Belgium we also have this service.