Yet Another Tire Question! - - Excellence in Motion
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post #1 of 12 (permalink) Old Oct 30th, 2005, 1:36 am Thread Starter
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Question Yet Another Tire Question!

Ok, a little different tire question. You finally make your tire selection. How critical is it to buy BMW/K-model specific tires? The stock Metz Z4's clearly have a "K" on the side. My new Bridgestone 020's do not as far as I can tell. Will this instantly turn my beloved into an unstable death trap? Please advise.
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post #2 of 12 (permalink) Old Oct 30th, 2005, 6:35 am
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i dont know.....but

i noticed the metz z6 has the "b" tire for oem bmw. more money. i bought the pirelli diablo, no "b" tire, works fine. most likely, the metz is marketing b.s. if u listen to them, they tell u to buy both tires matched, like the rear cares what is on the front. and vice versa. barfo!!!!!!!!!!!!!!! one industrious bs'er even suggested the z6 front tire "channelled" the water in rain to specific grooves in the rear tire, so buy both at same time. sometimes i think we americans, in our love affair with our bikes, lose all common sense. i'll bet u lunch if u buy the metz z6 without the "b" rating, their will be no downside, and u will be $25 richer. good luck
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post #3 of 12 (permalink) Old Oct 30th, 2005, 6:39 am
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I went through a similar thought process looking at changing my BT020's. When I checked the Bridgestone site and my tires I discovered that Bridgestone add a letter after 020 on the sidewalls to indicate an oem (BMW) spec. From memory I think letter F is generic. The tires still have all the correct high speed speed ratings etc. Most tyre depots and mail order will supply the generic letter code. The most expensive are likely to be from BMW agents. I have no problem with my K's handling and neither tire has the BMW approved letter on the sidewall - but they do have plenty of tread on and run true!

Now you begin to wonder why just about every bike manufacturer has a Bridgestone oem letter code and whether Bridgestone manufacture a totally different tire for every manufacturer. Commercially, you might appreciate that a bike manufacture ordering large tire quantities from Bridgestone is in a position to make a generic spec slightly different. You could also consider what might happen if Bridgestone stopped supplying the oem tyre as your bike got older and how other manufacturers can compete if you could only use one tire - do you scrap the bike?

As I am not a tyre expert, ride on tracks or at the maximum speed limits of my tyres or bike I take a pragmatic view. However, If my bike was in BMW warranty I might ask whether it would be affected.

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post #4 of 12 (permalink) Old Oct 30th, 2005, 6:48 am
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Yes there is a downside to buying a Z6 that isn't "B" designated. It doesn't last as long. Also the B tire is only for the rear of our K's. I have run the B & not B. Both are sticky but the B tire does last longer. About 95% of my riding is in the twisties here in East TN, Western NC and Northern GA.
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post #5 of 12 (permalink) Old Oct 30th, 2005, 8:21 am
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Yep, I think that you're looking for a "B", not a "K". I really don't believe that there is a safety issue at all with any 'quality' tire no matter what the rating, unless you're overloading in excess and speeding your arse off for any length of time. However, the wear may be a bit more premature. "B" is a higher load rating.

Do you know when a tire is speed rated, let's say a V-rated tire. That tire is speed tested to stay safe at 149 MPH for a period of 24 hours! That, to me, is one muf'n tough tire. You can look up the H, W, or whatever for speed rating, but that doesn't change that 24 hour test. When they "B" rate the tire, they just add more load for the same timed/speed test. How much more? I don't know.

For example:

I've used the non "B" M1s since they came out, and still use them from time to time for the back because they make my K handles so well. When riding hard, I only get 2-3K out of the back and 3-4 out of the front, but the softer compound is worth the performance/handling you get from them. I now only use an M1, non "B" tire for the front because of its steering characteristics that I like with the KRS. I haven't tried the "B"s yet, and I don't really believe they'll handle any better, nor do I believe that I get too many more miles out of them. I guess I'll try one day and see, but till then, I'm simply not convinced that there is much of a difference with our bikes, unless you're really cutting the road with 2 up. Otherwise, I think that perhaps with a big fat heavy hog, then there could be a considerable difference.

No current bike.
(previous: 01 K12RS (*RED*)

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post #6 of 12 (permalink) Old Oct 30th, 2005, 9:27 am
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The "B" is NOT an approved rating by anybody that I could find other than Metzler. I emailed everyone. According to Metzler, the B means that the tire has stiffer side walls for a heavier load (as previously stated by other posters). Other than that, the tread pattern and rubber and belts are identicle.

Michelin, Avon and Continental responded that they do not use the "B" indicator and that it was obviously an internal, private label since it is NOT a rating specified by DOT or any other government agency. Speed ratings ARE an industry standard; these are not!

Pirelli and Bridgestone did not respond to my emails.

I have used the OEM Z4 and Z6, both with the B label, Pilot Powers and now the Avons. To me, the Powers handled the best, followed by the Avons, Z6 and the Z4. For wear, the Powers were the worst, however, even though the Z6s lasted the longest, I feel that they are DANGEROUS! They went from looking like they would need to be replaced in a 1,000 or so miles (not yet at the wear bars) to showing the belts in just a couple of hundred. This has been reported by many on this site. I will NEVER use these again!

Just my $.02

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post #7 of 12 (permalink) Old Oct 30th, 2005, 11:32 am
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If its the same size, speed, and weight rated tire I cant see where safety could be much of an issue. However, when I couldnt buy an Avon for the rear to replace a damaged tire ,I went with the Metz. avon front with under 3,000 miles on it and a new Metz. Even my gf who doesnt ride much could tell the difference in handling.Bike felt like it was hinged in the middle. I left the Metz on for about 1000 miles just to be sure it was broke in, then put another Avon on the back.Sold the Metz for 30 bucks. When I needed tires next time, ordered Avons.
When I was a pup years ago we used to think one brand front and another brand rear could improve handling of certain bikes.Change the steering to quicker or slower.Still think it was true.It could be the Avon/Metz combo just didnt play well together on the K and my riding style.
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post #8 of 12 (permalink) Old Oct 30th, 2005, 12:24 pm
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Avon does have a "B" version FRONT with a heavier sidewall for GT type bikes. Stiffer sidewall as mentioned already. I had a front Avon non-B version start cupping on my R11RS so went with the B version this time. We'll see if it lasts longer or cups. Great tires though.

Mike Figielski
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post #9 of 12 (permalink) Old Oct 30th, 2005, 12:26 pm
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Originally Posted by htheater
even though the Z6s lasted the longest, I feel that they are DANGEROUS! They went from looking like they would need to be replaced in a 1,000 or so miles (not yet at the wear bars) to showing the belts in just a couple of hundred. This has been reported by many on this site. I will NEVER use these again!
I'll second that! Left Clemson for DGR (~100miles) with worn Z6s. By my estimate I had 1-2K left. Was planning on a weekend of gen-teel riding so wasn't concerned. Sat AM had a look before heading out - Uh oh! Can anybody point the wear bars to me. Maybe I need LASIK but I don'e see em.
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post #10 of 12 (permalink) Old Oct 30th, 2005, 12:32 pm
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Posts: 52 are correct...sort of....I went back and looked at my emails since I remember Avon saying the B was not an industry standard rating, however, they DO have a B just means something a little different. Thanks for catching that! Here is their response:

The “B” for Metzler may and most likely is for BMW markings (use). Avon Tyres “B” markings stand for something different (not BMW).

In general “B” versions AV45/46 – ST Sport Touring, AV49/50 – SP Sport; 120/70R17’s, 180/55R17’s and 190/50R17’s. The front’s are for motorcycles that have low level stability characteristics. And the rear’s are for motorcycles that require a higher level of ultra speed stability (such as on the German Autobahn). They have TUV approval on such motorcycles as Hayabusa, Blackbird, etc.. These motorcycles have a higher weight and speed rating. Not necessary to apply a “B” version to a lighter, less speed rated motorcycle.

Please feel free to revisit Avon Tyres website for your motorcycles fitment. Map – North America, Fitments – click, Make – BMW, CC – 1200, Model – K 1200 RS (5.50” Rear Rim) – 589 – 1997 -. 120/70R17 (58W) AV45 – ST, AV49 – SP, Pro – Series @ 36 p.s.i. cold, 180/55R17 (73W) AV46 – ST, AV50 – SP, Pro – Series @ 42 p.s.i. cold. No “B” version listed, “B” version not necessary.

Non “B” vs. “B” version tire case construction facts are as followed:

Non “B” “B”

Sidewall plies 1 Rayon Sidewall plies 2 Nylon

Tread plies 1 Rayon, 1 Polyester, Tread plies 2 Nylon, 1 Aramid

1 Aramid

So the question is are two plies of Nylon stronger then one ply of Rayon? This is a great unknown. Which came first, Nylon vs. Rayon for materials used in tire casing construction? So is the “B” version stronger in the sidewall? Unknown, it does weighs more.

Avon Tyres recommends non “B” version for your motorcycle.

Thank you for your interest in Avon Tyres.

Thanks, Keith

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