Next tyres will be high speed again - The Unofficial BMW M5 Messageboard (m5board.com)

MikeC · 1st July 2002, 12:52

It's been very silent here lately so I'm posting just something...

By the end of July my current set of tyres will be worn out and I'll buy a new one - Y rated and the speed governor will be removed again. I get more and more annoyed again by the virtual anchor being released at 260 kph

The difference: this time I try Bridgestone Potenza S03 Pole Position tyres (front: 235/45 ZR 17 94Y, rear: 265/40 ZR 17 96Y). A Michelin rear tyre would cost $/EUR 565, the Bridgestones cost half as much. I'm curious how they perform. At least on the Autobahn there should be no noticeable difference.

And they are available. At Michelin I get contradicting statements concerning the availability of those tyres. The Bridgestones are delivered on special order only but at least you can buy them

When this is achieved I will post a 300 kph video and an image of the speedometer with its needle going off-scale

(305+ kph).

What have I missed it...

...Mike

raymondw · 1st July 2002, 13:40

Hello Mike,

Please note that Y rated tires cannot take their full load at speeds above 270km/h. At 300km/h there is a derating of 30%. With a 2 ton car at speeds above 270km/h this is important.

I also had problems with the availability for the Michelin Pilot Sports for my E28 ///M5. I ordered them on 28 december 2001. But I had to wait untill the end of may before the 225/55ZR16 94Y arrived.

I am very interested with your experiences with the S03. I have heard mixed opinions about these. Some people rave about them and some cannot live with them.

As the rear SP9000 from my E34 ///M5 need replacement next fall, I am concidering the S03 PP or the Michelin Pilot Sport's.

Rgrds,

Raymond

MikeC · 1st July 2002, 14:21

Yes, I know about load index degradation. The front tyres are rated at 94Y which means they can take 670kg (at 270 kph). Fully loaded (2300kg) that would make 575kg per tyre (50:50 weight distribution!).

So... I was aware of the load index degrading to only 85 percent with Y-rated tyres at 300 kph: 670kg * 0.85 = 570kg. But the CSi's top speed without the governor is slightly over 290kph (rev limit in 6th - if left stock

- at 6000rpm) so the TÜV won't make trouble.

My source of information regarding tyres and load index is this. Where does your 30%-information come from?

I think the ultra-rare occasions when I'm on the track with the 8 might not be worth the extra money spent on the Michelins.

...Mike

raymondw · 3rd July 2002, 08:43

Mike,

The 70% figure is what was told to me by a rep. of Dunlop Netherlands when I called them about the speed rating of the SP9000 235/45ZR17 without W or Y rating.

Rgrds,

Raymond

Malcolm · 6th August 2002, 10:05

I have had a great run with Continental ContiSport Contacts on my E34 M5. Good handling at 200km/h cruising speeds in (sometimes)extreme heat conditions and good wear characteristics. I check the pressures weekly and have just replaced a set - 235's on the front and 255's on the rear.
My pleasure is driving my M5 'entheusastically', as designed and being able to do so in the Middle-East.
I have had Pirellis de-laminate at 220km/h (on the rear luckily) and Dunlops loose chunks of tread, but the Conti's have been perfect for me.

MikeC · 6th August 2002, 10:45

How's the wear of the Contis on an M5? From at least two other 8 series owners I have heard that they have about half the life expectancy of any other tyre (and even less compared to the Michelins, at least on an 8 series).

...Mike

Malcolm · 10th August 2002, 12:34

I logged 60,000km (=approx 37,000miles) on the Conti's and the rear's had more wear than the fronts. I changed the set as the rear tread wear bar was there, and one of the fronts had slight sidewall laceration as the result of running over something
'foreign' and unseen on the road at night.

By the way, I am looking at this site for info and insight, as I am considering buying a '91 850i that has been offered to me.
I love the design shape of the '8' series.

spikus · 2nd October 2002, 12:06

G'Day Malcolm

If your interested in buying an 8 then look for something after 1993. A revised version came out then which included the active rear steer. As an 850 Csi owner I can tell you this is some wheird experience when is kicks in. Also many of the electric glitches that occurred with earlier models where fixed.

Check out the website :

http://www.bmw850.de/english.html - it has loads of info

Thanks

Spike

MikeC · 22nd July 2003, 21:04

Bridgestone Potenza S03 Pole Position vs. Michelin Pilot Sport (SX? MXX3? soryy, I have forgotten):

Okay, as Michelin does not manufacture tyres the size of 265/40 ZR17 any more I was forced to go for the Bridgestones. They have a lot of negative profile so I was worried a bit about their grip level.

Because of different road surfaces, there were some spots where I could have tyre squeal in 1st gear without using the clutch. The Bridgestones have awesome grip in that respect. Not even the tinyest sound come from them where the Michelins were going up in smoke. That was surprising.

Also surprising was that the high speed cornering ability is vastly inferior to that of the Michelins. I was a bit disappointed to see that corners that could easily be taken at 270 kph before are now impossible to drive through at that speed. 250 and the first warnings are coming, 260 and you know that you are about to crash if you were pushing it further.

In a straight line, however, the Bridgestones are great. I haven't been faster than 280 with them yet, but that will change on Sunday

Track use: Well, I think I'm not on a race track often enough and by far not experienced or knowledgeable enough to make a statement here. The Autobahn is where I am at home.

Wet roads. All say the Bridgestones outperform the Michelins in the wet. But even with the Michelins I haven't even (didn't want to) come close to theirs in wet condition. So no statement either.

Road noise is acceptable. I don't know if the slightly whining noise has been there before and just gone unnoticed or if it's really the tyres...

Let's see how long they last. I guess I'll then move to 18" wheels (and away from my beloved 'throwing stars') and buy Michelin again - because high speed cornering is what matters to me most.

...Mike

MikeC · 4th August 2003, 11:02

Okay, maybe it will get better if the tyres are worn down, but even in a straight line and extreme speeds (exceeding 300 kph) the Bridgestones are inferior to the Michelins.

The car is more 'wobbly' and not as sure-footed as before, although you could still take a hand off the steering wheel at top speed and work on the radio.

When braking hard you need both hands again. The car becomes quite unstable and starts wandering off line. This becomes noticeable at 250 and quite scary beyond 280 if you don't expect it to happen. So I'm telling you now

Bottom line: if Michelin doesn't manufacture the high-speed tyres you need, go for other wheels for which they still do. At least if you have an 8-series.

...Mike