"B" Rated tires: Why do we need them on our BMW bikes?

[Lone_RT_rider]

So I ordeded I set of tires on the rule of thumb from this board that we somehow need the B rated tires for the R1200RT. Can someone please explain to me why this is? When I placed the order, the vendor supposedly had them in stock, now they do not and are asking if I would take a standard tire.

 

My question is, what benefit do I get by having a B rated tire on my R1200RT?

 

Shawn

[malcolmblalock]

It's my understanding that the "B" tires are designed for heavier loading, such as riding two-up. They have stiffer sidewalls and, I think, another ply in the tread area to accommodate the extra load.

 

Presumably, if your riding does not include lots of riding where the bike is carrying a lot of weight, the "B" tire is not necessary. And, a lot of riders routinely ride two-up without using these heavier-duty tires.

 

If I've misstated this information, someone else with more correct information please speak up.

[Lone_RT_rider]

Presumably, if your riding does not include lots of riding where the bike is carrying a lot of weight, the "B" tire is not necessary.

 

I wonder how they define "a lot of weight"?

 

Shawn

[dirtrider]

Morning Shawn

 

Your really need to E-Mail or call the tire manufacturer of the tire you intend to buy.

 

That additional tire rating number can mean different things on different tire brands. Sometimes it means more load carrying capacity but in other instances it can mean a ply difference, or a ply angle difference, or even a side wall difference to prevent rim damage when mounting.

 

As long as the tire’s load & speed rating are within your expected usage I’m just not sure that you get any added gain from the more expensive B (or BMW) rated tire.

 

Personally I don’t know anyone in my riding/ motorcycle friend group that uses the B (or BMW) rated tire anymore. Way back some tried the BMW rated tires & found no difference in performance or tire life. In fact one of the local BMW dealers only carry the standard tire & have to special order the B rated if someone insists on it.

 

[Lone_RT_rider]

Morning Shawn

 

Your really need to E-Mail or call the tire manufacturer of the tire you intend to buy.

 

Done, but I am not sure how much information I'll get back when they only allow 100 characters for the question.

 

Shawn

[Firefight911]

What rule of thumb are you talking about?

 

LINKY

 

The "B" has no greater capacity or load rating. It is just a slightly different design.

 

Many times, tires have different designations due to OEM spec tires that the manufacturers spec to provide a certain handling characteristic, eg.; steeper profile, mid corner stability, etc.

 

If you are always running at GVWR then maybe, just maybe, there might be some advantage to a "B" fitment tire such as the Michelin brand offers, for example. Most likely, you will find your wallet is lighter which directly offsets the additional load you are carrying.

 

I've spoken at length with Michelin about this on the phone. You are fine to run the standard tire. Your wallet will thank you as well.

[tallman]

DR,

And yet, I've run about 8 sets or so of Z6's, only one of which was not the proper rating for my GT's rear tire.

Out of all of those tires and miles, the only one that wore out early was the incorrect rated tire.

On all of the others, consistent mileage, wear, etc.

Merely anecdotal but it does cover a lot of miles.

YMMV

[Firefight911]

Yes, Tim, but the "B" designation has nothing to do with ratings for load, etc. Both the "B" and "non-B" carry the exact same load rating.

[dirtrider]

Afternoon Tim

 

I also run Z-6’s (Z-8’s now)-- My finding on my RT is just the opposite of yours as I don’t run the “B rated” Z-6 replacement tire & so far every non B rated Z-6 has out mileaged the OEM Z-6 that came on the bike.

 

Who knows why, somewhat the same roads but I have no idea of how close the average speeds, or how close the average temps, or how close the extended loads, or ????. The only thing I’m consistent on is the tire pressures.

I never looked at the tire build date on the OEM tire but all my replacements come from Tucker Rocky & with their tire turnover rate the build date is always only a few months old or newer.

 

[FlyingFinn]

 

I wonder how they define "a lot of weight"?

 

 

 

 

I have no useful tire information to offer.

[tallman]

I didn't say B, and talking GT, GT had a C or K, whatever, only comparing a manufacturer's recommendation (use this version) to using another, and what I had happen.

May not matter with this version tire and the RT.

Just like running regular/premium.

YMMV

Best wishes.

[NCStephen]

From my talk with Michelin, The B tire are for the heavier sport tourers. I would think the RT would not be included in this. They said the tire had stiffer sidewalls to flex less but load limits and such were the same.

 

At the time I was rushed to get a tire and didn't get a B. I have used both the B and standard Michelin PR2. They both worked with similar mileage. I also didn't use that tire standard tire for hardly any 2 up riding. Still I know that my bike IS in the list for B version of the tire.

 

Also, in talking with a vendor that does lots of tires for sport and sport tourers, in the choice between Michelin Pilot Power and Dunlop Q2, the nod went to the Q2 for the same reason. Overall it is a stiffer tire and thus should have less flex on heavier bikes.

 

I have an 03 K-RS and it always has the bags on it with maybe 20 more lbs of stuff. So wet bike with luggage and stuff about 680 lbs, not a light weight by any means. (wet weight of an R12RT 570 lbs, the FJ1300 wet weight is also about 640). I would think, my opinion, that the RT would be fine on either tire. If you do mostly two up, why not spend the extra 30 bucks and get a tire to better handle the weight you will be carrying. If you had a B tire and not running the extra weight you might work on lower pressure and finding the point where temp is enough to slightly raise tire pressure (10%) and still be compliant enough for road work. just my $0.02.

 

NCS

[Guest Kakugo]

From my talk with Michelin, The B tire are for the heavier sport tourers. I would think the RT would not be included in this. They said the tire had stiffer sidewalls to flex less but load limits and such were the same.

 

Michelin list their 180/55 "B" tyres as "BMW specific". Nothing more, nothing less.

The difference in construction is one extra ply in the sidewall to increase overall stiffness.

While the ordinary tyre is 100% capable of handling a fully loaded bike in all safety there may be some flexing issues affecting handling under particularly aggressive riding.

There aren't that many BMW bikes fitted with a 180/55-17 tyre: the most recent Hexhead and Camhead and the "Wedge" K-bikes.

You may be spot on in your analysis: the K-bikes are heavier than boxers, rated to carry more load and, more critically, capable of much higher speeds.

I presently have a "B" PR3 rear which is nearing the end of its thread. Next up I will fit an ordinary PR3 and see if there's any difference.

I love to be a human guinea pig...

 

 

[Lone_RT_rider]

I presently have a "B" PR3 rear which is nearing the end of its thread.

 

Can I ask where you purchased the B PR3? There are quite a few places with them on backorder at the present time.

 

Shawn

[Guest Kakugo]

I presently have a "B" PR3 rear which is nearing the end of its thread.

 

Can I ask where you purchased the B PR3? There are quite a few places with them on backorder at the present time.

 

Shawn

 

Local tyre shop near my home here in Italy... they had both the regular and the B rear available but, curiously, PR2 were on backorder.

[CoarsegoldKid]

I normally run "B" rated because the extra plies tells me the tire is sturdier against road hazards. I have a lot counting on the tire. I don't mind the 24 extra bucks. I could be wasting money but it ain't the first time.

 

I recently went to the non-B rated PR3 due to backorder issues. Posts pretty much tell it like it is. I have a stack of used tires outback so I read the info on the side walls of:

PR2 B rated

Tread 3 polymide plies 1 aramid ply

sidewall 3 polymide max load 805lbs @ 42psi cold

PR3 non-B rated

Tread 2 polymide plies 1 aramid ply,

sidewall 2 polymide max load 805lbs @ 42psi cold.

 

[tallman]

Thanks Joe.

That shows there is a difference between the two.

At least to me that extra ply in 2 areas means something.

Ride safe, wear out those tyres.

[racer7]

I have run the B and non-B veersion of the PR2. When the bike is loaded for touring there is a discernible difference in handling with the B tire- its slighlty sdtiffer sidewall

"crisps up" the handling response a modest but noticeable amount. I find it a bit more predictable and likeable than the non-B. Slightly stader with a more uniform turn in might be another way of describing the handling difference under load.

 

BUT, I can also tell when my tires are a few lbs low without gatting out a gauge- comes from lots of time adjsting tires at the track. If you're one of those who is surprised when you gauge tells you your tire is 5 lbs low, then you proably won't be able to tell the diffrence anyway- so save the money. As noted- its not about load and in my hands the B does not have any differet tread life than a non-B

[John Bentall]

Interesting thread,

 

I have read that the heavy-duty spec tires offer some folks greater tire life and others sharper handling.

 

I am not privy to the details of how BMW "approve" their tires. I am not quite sure how much longer it will be mildly illegal in Germany to fit non-approved tires, as the tide seems to be turning on this ruling.

 

However it is legal in Germany to ride a R1200RT (or any other bike) at 125mph for 2 hours 2-up & fully laden for touring in the heat of summer.

I do not do this. However, if I did, I might consider swapping changing my standard spec tires for a heavy duty set.

 

John

[94aero]

I guess I need to move to Germany. It's sure not legal in Kansas, I've tried....

[dirtrider]

Interesting thread,

 

I have read that the heavy-duty spec tires offer some folks greater tire life and others sharper handling.

 

I am not privy to the details of how BMW "approve" their tires. I am not quite sure how much longer it will be mildly illegal in Germany to fit non-approved tires, as the tide seems to be turning on this ruling.

 

However it is legal in Germany to ride a R1200RT (or any other bike) at 125mph for 2 hours 2-up & fully laden for touring in the heat of summer.

I do not do this. However, if I did, I might consider swapping changing my standard spec tires for a heavy duty set.

 

John

 

 

Morning John

 

 

Keep in mind that adding extra sidewall plies is a trade-off of allowing bit of more tire lateral stuffiness at the trade off of higher tire running temperatures at very high speeds.

 

[NCStephen]

Interesting thread,

 

I have read that the heavy-duty spec tires offer some folks greater tire life and others sharper handling.

 

I am not privy to the details of how BMW "approve" their tires. I am not quite sure how much longer it will be mildly illegal in Germany to fit non-approved tires, as the tide seems to be turning on this ruling.

 

However it is legal in Germany to ride a R1200RT (or any other bike) at 125mph for 2 hours 2-up & fully laden for touring in the heat of summer.

I do not do this. However, if I did, I might consider swapping changing my standard spec tires for a heavy duty set.

 

John

 

John, of course you don't do this. You would have to stop for petrol at least once if not twice. So ride faster in order to keep your average up.