Metzeler Z8 PSI

[kgerry]

anyone know what the Z8's should run at PSI-wise?

[WestyLancs]

Metzeler website merely says 'Check the vehicle handbook.....'

 

link here

 

Not much help I suppose.

[blackyam]

Hi. I'm not sure what Z8s should run, but on my R12RT I run my Z8s 40F and 42R. YMMV.

 

---John.

[Peter Parts]

Within broad limits, there is no rule or prescription and that includes the "10% rule" that somebody is sure to bring up. The error-band in measuring and applying that "10%" is larger than the range between too high and too low - so it can't be useful unless you arrive from a distant planet and don't know if you should use 2 psi or 1000 psi.

 

You start with a highish pressure and you lower it bit by bit until you have more squigglies than you'd like. Then you raise it a little bit, ride to confirm, and then measure when cold the next morning and adjust as needed.

 

No rule will tell you the what your personal right balance is between comfort and handling precision. Rely on your own judgment.

 

Ben

[lkchris]

Metzeler rep gave presentation at dealer last week--recommends running at max pressure (see sidewall) all the time. Brochure basically does, too. This for longest tread life, I.e. miles. I'm not doing it.

[Peter Parts]

Metzeler rep gave presentation at dealer last week--recommends running at max pressure (see sidewall) all the time. Brochure basically does, too. This for longest tread life, I.e. miles. I'm not doing it.

 

Kent -

 

Please confirm there are no typos in your post.

 

Ben

[RTJohn]

I chatted with a Michelin rep a couple of years ago, he said the same thing as the Metzler guy. Max cold psi all the time. That's what I do and have noticed no ill effects. The Long Beach motor officers do the same with whatever tires they have their bikes.

[Peter Parts]

There may be no ill effects as far as handling goes from excessive high pressures. Prolly great for handling.

 

But tire pressure is a matter of balancing comfort (AKA ability to ride the distance without losing your dentures) with handling. Above a certain pressure, there's little gain in handling. Of course, below a certain low pressure, you're in for big trouble even if it absorbs the cracks in the concrete slabs.

 

Only two parameters: choice of tire (like smarter modern tires like Bridgestone BT023) and air pressure. No other ways to address this perpetual trade-off that I know of.

 

Alas, lots of self-imagined brownie points using very high tire pressure and then (implicitly) boasting about your ability to (a) withstand discomfort and (b) being the ultimate great handling rider.... but no brownie points for boasting "I found a great compromise...."

 

I couldn't say what those pressures are or point a finger at anybody posting here so far. Just sayin'.

 

Ben

[philbytx]

Well,

Adding some factual data to this debate:

HERE is a link to the Oz Metzeler site giving out recommended pressures on various tires in bar. Nowhere here does it say max sidewall all the time!

Most show psi figures around 36 through 42psi

 

Just sayin...

[lkchris]

Metzeler rep gave presentation at dealer last week--recommends running at max pressure (see sidewall) all the time. Brochure basically does, too. This for longest tread life, I.e. miles. I'm not doing it.

 

Kent -

 

Please confirm there are no typos in your post.

 

Ben

 

None

[Sonor]

I'm on Z6s and love them. Can anybody speak to the differences between the Z6 and Z8? (don't mean to hi jack the thread)

[RTJohn]

I had Z8's on my RT. Great tires. The front sidewall said 36 psi cold, the rear 42 psi cold. That's what I ran them at. The PR3's I have on now say 42 psi for both. That's what I run them at. No problems noted.

[Paul In Australia]

I had Z8's on my RT. Great tires. The front sidewall said 36 psi cold, the rear 42 psi cold. That's what I ran them at. The PR3's I have on now say 42 psi for both. That's what I run them at. No problems noted.

Hi

Do you find the bike to be "bouncy" with 42 in the front tyre?

Regards

[RTJohn]

Hey Paul. Honestly, the only thing I noticed was less cupping and an increase in tire life. I routinely get 15k miles on a set of tires.

[dirtrider]

Morning-----

 

What I have never understood is that a rider will obsess to the 1/2 ounce over BMW's specified oil fill requirements, or over precise final drive refill requirements, or fiddle with 2 feeler gauges to meet BMW's exact valve adjustment specs then not listen to BMW's suggested tire pressure specs.

 

BMW spent a lot of time & many many miles of testing defining tire response, wear, ride quality, ABS braking function, safe high speed pressure increase, etc.

 

[Paul In Australia]

Excellent point

 

[RTJohn]

I thought that's what made us so much fun to be with!

[tallman]

"BMW spent a lot of time & many many miles of testing defining tire response, wear, ride quality, ABS braking function, safe high speed pressure increase, etc"

 

Without a doubt.

 

But.

 

Did he weigh the same as I do?

Did he ride roads composed of the same material?

Was he riding in the same ambients?

Is he as slow as I am?

 

And.

 

Just as the mothership has revised certain things, like FD fill amount, FD "lifetime" fluid, not to mention the horrible capitualtion wrt turn signal switchgear and ensuing problems...

 

Just some random thinks.

 

OH, and I don't obsess these past 8 yrs over the oil situation like I did the previous 37.

K's don't act like Boxers do.

 

Heck, we all do it sometimes.

"The bulletin goes on to NOT recommend using a standard (non canbus) charger without disconnecting the battery first (but a lot of us 1200RT owners ignore this recommendation without any issues at all)."

from another thread.

 

[dirtrider]

Morning Tallman

 

Did he weigh the same as I do? --- more than likely the testing was done using a number of rider weights, various ballasted passenger weights, varying pannier & top box weights, etc. Testing is testing (not just riding around) so if the BMW motorcycle testing & validation is based on industry standard testing formats then the entire gambit of weights & possibilities were tested & validated.

 

 

 

Did he ride roads composed of the same material? --- Probably close, there are specific test roads in every country that approximate the surface & texture of roads throughout the world. If none available then there are various testing facilities that have specific roads & road surfaces available for test & validation.

 

 

 

Was he riding in the same ambients? --- I can't imagine any major motor company that didn't test in most available ambients, altitudes, grades, weather, etc. They sure couldn't tune the fuel injection & spark without testing & validation in a number of altitudes, weather, ambient temps.

 

 

Is he as slow as I am? --- First off who says it is a HE, might as easily be a she. As to the riding/testing speed?- again I just can't imagine ANY major motor company not testing at all speeds, aggressiveness, wind conditions, vehicle loadings. No way to validate the full range ABS braking function without testing at about all speeds & weightings.

 

 

Keep in mind that BMW didn't just test one bike with one set of tires, or one rider. I'm sure they tested many bikes (with many iterations of content) using a number of riders & tire combinations riding many different road surfaces. Probably some done on dynos, some testing done in other countries, & some done on test tracks.

 

It wouldn’t surprise me at all if the total product development & validation test miles greatly exceeded 1 million miles.

 

 

 

 

 

[kgerry]

i just bought the bike new and the dealer had it set at 2.6 bar front (37-38 psi) and 3.1 bar rear (44-45 psi).... sound about right?

[philbytx]

+1

Also, empirical evidence allows you to use the manufacturers settings as baseline then modify to your own riding style, bike loading and local road surfaces. My own empirical evidence has me running the following pressures on both bikes (R1100R and R1150RT)

Solo

Front 37 (BMW specs 31.2 to 35.57)

Rear 39 (BMW specs 35.47 to 41.26)

Touring (Two-up)

Front 38

Rear 42

 

Our local road surfaces are chip and seal and its like riding on VERY large grit sandpaper.

I used to get waaaay better tyre mileage when riding slab "up north" and now consider myself very fortunate if I get 5000 from a front and 4000 from a rear tire!

I'm trying the new Pirelli Angel ST EMS on both bikes as the Conti Road Attack II's seem to wear out very quickly. I still have an RAII on my R but I may have about 1k left on it (if I'm lucky).

Then, if the Pirelli's don't work, I will probably try Shinko's. At least I won't be going through the dollars as quickly !

 

 

 

 

[Peter Parts]

Ah.... Tallman (who posts often impress me favorably) in his reply to Dirtrider (whose reply to Tallman left me cold this one time) left out something important:

 

there has been a clear long-term trend upwards in recommended tire pressures on the bike "sticker" from BMW. The reason for that is reduction in tire stiffness (which I think is due to going radial) and which has obliged the bike makers to compensate for by changes in other pieces of the suspension (its a whole suspension "system" after all).

 

For sure, the sticker pressure on Airheads may be dangerously low for today's tires. I can't say if that is as true for all Oilhead model sticker pressure in 2013.

 

But my point and Tallman's is that sticker tire pressure is there for CYA/regulatory reasons and isn't a good guide after a few years. Do you know the joke about the clock that is right some of the time?

 

Ben

[dirtrider]

Afternoon Ben

 

Seeing as this thread is about the Metzler Z-8 tire pressure on a 2013 1200RT I'm not sure what airhead tires or clocks have to do with that.

 

You don't seem to recommend going by the BMW specifications in the riders manual so you must have a lot more experience with the Metzler Z-8 tire on the 1200RT than BMW does.

 

How many miles have you traveled using the Z-8 tire on the 1200RT?

 

[tallman]

DR,

Not being contentious, just know that almost universally,

in our area, covering thousands of bikes sold and repaired, almost all did better (more miles/fewer rider complaints/etc) w/higher

tire air pressure than the BMW sticker said to use.

 

Was this "better" or "safer".

Dunno.

I do know that the same riders, on the same bikes, riding the same roads, were happier (self reporting anecdotal no doubt) according to their feedback to us, when tire pressure psi upped a bit from BMW specs.

 

As Ben said, a lot of changes over the years and I haven't sold a new BMW for several years now so I'm not up to date on the camhead specs.

 

If I were taking an RT on a long dirt/hard gravel road, and had a compressor w/me as ussual, should I drop tire pressure a bit, or, leave it alone?

BMW specs say remain constant.

Not so sure.

So if there are outliers, then the specs are guidelines, IMO,

not absolutes.

For the record, about 8-9 sets of Z 6's here, but no Z 8's.

[dirtrider]

Afternoon Tim

 

I couldn't say how many sets of Z-6's I have run in the past without looking it up but am on my 3rd set of Z-8's right now. (until the Z-8 was introduced the Z-6 was my personal tire of choice)

 

I don't get great motorcycle tire mileage (never have) as I am a fairly aggressive rider, but one thing I can say about the Z-8 tires on the BMW 1200RT is I get very even wear, no cupping, feathering, or odd wear patterns. I run BMW recommended tire pressures most of the time & will only jack the pressures up if riding long distances in predicted heavy rain as I ride fast (like real fast) even in the rain & elevated tire pressures raise the hydroplaning speed a bit.

 

[tallman]

That should be another thread so MItch can explain it...

[Peter Parts]

Afternoon Ben

 

Seeing as this thread is about the Metzler Z-8 tire pressure on a 2013 1200RT I'm not sure what airhead tires or clocks have to do with that.

 

You don't seem to recommend going by the BMW specifications in the riders manual so you must have a lot more experience with the Metzler Z-8 tire on the 1200RT than BMW does.

 

How many miles have you traveled using the Z-8 tire on the 1200RT?

 

I object to your thinly veiled effort at attack sarcasm under the illusion of asking me questions.

 

My point is that the sticker is not trustworthy, for the reasons given. And in proportion to the time separating the model-years of the introduction of the bike and the tire. I'll sticker to that.

 

Ben

[dirtrider]

Afternoon Ben

 

Seeing as this thread is about the Metzler Z-8 tire pressure on a 2013 1200RT I'm not sure what airhead tires or clocks have to do with that.

 

You don't seem to recommend going by the BMW specifications in the riders manual so you must have a lot more experience with the Metzler Z-8 tire on the 1200RT than BMW does.

 

How many miles have you traveled using the Z-8 tire on the 1200RT?

 

I object to your thinly veiled effort at attack sarcasm under the illusion of asking me questions.

 

My point is that the sticker is not trustworthy, for the reasons given. And in proportion to the time separating the model-years of the introduction of the bike and the tire. I'll sticker to that.

 

Some things "BMW" knows and some things it doesn't. Some pronouncements (like the ridiculous recent statements about the R90s we've been suckered with) are driven by unworthy motivations, with no relation to engineering. Some engineering designs (like multi-electrode spark plugs) are introduced for mysterious corporate purposes we can only guess at. Sometimes BMW obliges their customers to be part of their R&D (like with inept early EFI systems). Then there are BMW saddles....

 

And some things, BMW does real good too.

 

Ben

 

 

Evening Ben

 

No sarcasm intended, just trying to understand your background in using the Z-8 tire on the 1200RT?

 

You say the (BMW) sticker is not trustworthy so therefore I assume you must have some sort of background using the Z-8 tire on the 1200RT.

 

[tallman]

"And some things, BMW does real good too."

 

Amen to that.

Probably the main reason many, including me, found this place.

[Peter Parts]

OK, apology accepted.

 

Another parameter nobody has mentioned is temperature. Sporty/sticky tires - at any pressure - are deadly in cool climates. So tire choices and pressures vary depending.

 

A rider in Canada, like the OP, has to take care in evaluating advice from riders, however skillful, in warmer places.

 

Ben

[dirtrider]

OK, apology accepted.

 

Another parameter nobody has mentioned is temperature. Sporty/sticky tires - at any pressure - are deadly in cool climates. So tire choices and pressures vary depending.

 

A rider in Canada, like the OP, has to take care in evaluating advice from riders, however skillful, in warmer places.

 

Ben

 

Evening Ben

 

The reason nobody mentioned "Sporty/sticky tires" is because this thread is about the air pressure for Z-8 tires on a 1200RT. To try & change the direction to Sporty/sticky tires would be hijacking the thread.

 

[philbytx]

FYI -

HERE is the definitive word from the Metzeler Corporate website. As DR stated, it basically says that you need to RTFBM .

 

Interesting to note that the Oz Metzeler site isn't in line with corporate - HERE. As it actually gives out tire pressures (in bar) for the ME880 and then a range of "dual purpose" tyres.

 

 

[Paul In Australia]

Sort of ends the discussion really doesnt it. Virtually all tyre manufacturers refer you to the vehicle makers recommendations. We may all have personal pressure likes but the vehicle maker suggests design pressures. I use the vehicle manufactures recommendations

Regards

Paul

[lkchris]

Not really ... here's a direct quote from Metzeler literature:

 

Recommended tire inflation pressure for the motorcycle can be found on the motorcycle's tire placard or in the owner's manual. However Metzeler has found that air pressure suggestions as shown (based on load) in the the table below will improve mileage and customer satisfaction.

 

Since about 90% of all comments about a tire seem to center on how long it lasts, this is important to tire manufacturers. Metzeler at least will publicly state that increasing pressure increases tire life. They clearly feel confident this approach is not significantly dangerous.

 

Given sensible recognition that motorcycling is simply an expensive hobby, I'm not much concerned about tire mileage and associated expense but rather with the fun in it all and therefore I'm going to follow BMW's recommendations.

[philbytx]

But that is ONLY in Australia LOL!

[dirtrider]

clip-- here's a direct quote from Metzeler literature:

 

Recommended tire inflation pressure for the motorcycle can be found on the motorcycle's tire placard or in the owner's manual. However Metzeler has found that air pressure suggestions as shown (based on load) in the the table below will improve mileage and customer satisfaction.--clip

 

Afternoon Kent

 

So what is the Metzler recommended tire pressure for the Z-8 in the 1200RT BMW sizes.

 

 

 

[lkchris]

In the brochure noted they aren't much different than BMW's recommendations save for the category "Rear tires marked with a max 50 psi on the sidewall." Then it's

 

solo 44-46

2-up 46-48

2-up, big load 48-50

 

Remember, in person the Metzeler rep says sidewall max psi always---again this being to achieve longest life/mileage.

[dirtrider]

Evening Kent

 

The 50 psi max on sidewall definitely doesn't apply to the Metzler Z-8 in BMW sizes so that data doesn't apply.

 

So that must mean the "In the brochure noted they aren't much different than BMW's recommendations" must apply.