Tire Pressure

[pjh23bmw]

I have about 3000 miles on my 07 RT. I run the tires at 38/42 psi front/rear. Once I get on the highway and hit 65 MPH and over the bike becomes skittish, does not hold its line well, and is very sensitive to the slightest cross wind. I am holding the bars loosely so that's not the issue. Is it the tire pressure, the suspension setting, or something else?

[ShovelStrokeEd]

Unless you are up to the maximum load rating of your rear tire, you should not be running that much pressure back there. I think you might be much happier with something like 37/39 or so.

 

If you can find the time and a willing scale operator, go to the local truck stop and weigh your wheels individually. Now look on the tire and find the maximum rated load of the tire. Take your weight from the truck stop as a percentage of that and adjust to the maximum inflation pressure stamped on the tire.

 

So, 675 lbs @ 42 PSI, for example and your laden wheel weight is 560. That would give you 83% of 42 PSI or 34.8 lbs cold inflation pressure. Add 2 lbs for the Gods of tire wear and your at around 37 PSI. Drop the front 2 lbs lower and your probably about perfect for your weight on that bike.

 

I used to run around over inflating my tires in the vain hope of getting better milage out of them but, I have been running less and less air and getting more compliance out of them as a result with no noticable reduction in tread life. Probably due to the fact that there is more tread in contact with the road at the lower pressures therefore the load is spread over a larger surface area.

 

It would certainly explain the inflation pressures recommended in your owner's manual.

[Stan Walker]

I used to run around over inflating my tires in the vain hope of getting better mileage out of them but, I have been running less and less air and getting more compliance out of them as a result with no noticeable reduction in tread life

 

Me too. I'm currently running my Z6's at 34/38 and the current set has 12749 miles on them. I think that's a personal record for any set of tires on my RT's including 1 set of Pilot Roads.

 

I check them every week for any sign of cords as the rear Z6 wear indicators are too far to the sides to be trusted. Most weeks I only ride about 250 miles so this should work out OK. Needless to say the replacement set is leaning against the HF tire changer.....

 

As to why? I can only speculate......

 

Stan

[jakfrost]

You don't say which manufacturer's tires you are running on. If they are the Metzler Z6's you might as well save yourself a year of frustration trying every tire pressure from 34 to 42, every possible suspension setting, every possible combination of the above 2 factors, and go straight to another manufacturer.

 

I went to Avon Storms. Others have good success with Pilot Roads, etc.

 

The bike still is 'nervous' in strong wind conditions but feels much more inherently stable, as in it is moving around but not going to toss you, kind of stability.

 

The 'weaving' that came to life with the Z6's, and on occasion felt like it might like to end mine, is gone.

 

Caveat...not everyone has had this experience with Z6's so opinions vary.

 

Jim

[pjh23bmw]

Great input so far. I am running Bridgestones, and I'm not sure if that comes into play. My other observation is that because of the fairing and the way the bike is built there is no place for cross winds to pass through the frame, so the bike and rider become "a sail." I have several friends with Harleys and they report no such issues. I've never ridden a HD so I can't comment. I'm going to try 34/38 psi and report back. I've only been riding about 5 months and being tossed around at 65-70 mph is no fun at all.

[onedae]

"My other observation is that because of the fairing and the way the bike is built there is no place for cross winds to pass through the frame, so the bike and rider become "a sail."

 

if you really want to feel a sail, ride the new KGT. The slab sided body is super sensitive to wind - more than any bike I've ever ridden.

[Dave_in_TX]

I've only had my 1200RT for two months and 4000 miles after 17 years of riding Kawasaki Voyagers but I haven't noticed any tendency for the RT to become "skittish" or "react to the slightest crosswind". Of course the Voyager with a full fairing doesn't provide any place for side winds to pass through either but it's also 200 pounds heavier than the RT. I'd say the RT is almost as stable in cross winds as the Voyager. BTW, I'm running Bridgestone BT020 tires.

[AZKomet]

What type of tires?? I have the Avon Storms and I run 40 f 44 r......yes....When I had my LT it was 46 front and 50 rear. I have no problems with suspension on my RT. Maybe a check up is in order...try the tire pressures first. Good luck.

[KDR]

I've had the same experience on my R12RT and am not yet convinced that it is tire pressure or crosswind. The only constant has been speed. Above 60mph is the only speed that it happens, but it doesn't always happen when above 60mph. I've run a number of different tire pressure and suspension settings and, given the randomness of occurrence, haven't yet found the "perfect" solution.

 

The only similar situation was on my K75. When I had the cases on and went above 70mph I experienced a similar problem. Without the cases it never happened. My R12RT lives in a public garage so removing the cases isn't an easy option for me, but if anyone else tries it and finds success, please let me know.

[pjh23bmw]

Re: KDR's comment:"The only constant has been speed. Above 60mph is the only speed that it happens..."

 

I agree. The bike is rock steady until about 65 mph. It may not be crosswinds, tire pressure, or suspension. Perhaps an oscillation is occurring under just the right circumstances which is interfering with the handling. Has to do with all kinds of factors and frequencies. Hope we don't need a physicist to figure this out. Before I bought mine I drove one about 50 miles, mostly on the highway, and didn't have a problem. Time to talk to the dealer.

[ShovelStrokeEd]

Some other stuff just occurred to me.

 

First off, we can put the aerodynamics thing to bed. These bikes are designed and built in Europe where speeds are typically much higher than 60 or so mph and they do fine. I have not had the pleasure of riding a new RT yet but have ridden enough BMW's, at triple digits, over the last 47 years to know this shouldn't be an issue.

 

Pavement and tires can have a big effect here. Again, can't speak for the roads out there but, if there are rain grooves, quite common in the west, that could be part of the problem. Even rough chip seal can give something of an unsettling effect. Some tires are much more prone to nibbling on these kinds of road surfaces than others.

 

Another factor, although I confess I have never really noticed it on my bikes, is that the geometry of the BMW front suspension is unique in motorcycling in that the wheelbase actually gets longer as the suspension compresses. You might be feeling this subtle change.

[KDR]

PJH, let me know what you find out and I'll do the same.

[pjh23bmw]

Re: Shove/Stroke Ed's observations. True about the rain grooves, that compounds the problem. What I have observed is on ungrooved, smooth pavement. The bike does start dancing around over 65 mph, so something is going on. That is occurring on calm days, and on windy days, forget it, it's a nightmare.

 

I dropped the tire pressure to 34/38 and will report back after I have tried it out for another day.

[boatzo]

Every time I read another post on tire pressure, I end up confused (again).

 

I have been keeping a log of all the different pressures the different members have posted and they seem to be all over the place. Understanding, of course, that there are a lot of factors to consider, weight, loading, etc.

 

My qusetion to the more informed is, does it make a difference what brand/model tires one is using as to what the correct pressurs should be?

 

I was running 34f/38r then stepped up to 38/40. I don't notice much difference in handling but it appears that the tires show wear more quickly (in the center) at the higher pressures.

[tobyzusa]

Every time I was running 34f/38r then stepped up to 38/40. I don't notice much difference in handling but it appears that the tires show wear more quickly (in the center) at the higher pressures.

 

Maybe, but at the lower pressures you have to watch out for cupping.

[azkaisr]

Sent you a PM

 

Kaisr

[AceVentura]

I run my tires at about 34/38, I have about 800 miles on an '07 with Michelins. At highway speeds, even over the limits (only we needed ) my RT is as solid and stable as a rock. I have not riden in extreme crosswinds, but I have gotten hit with some big gusts of wind.

[Bheckel169]

Ace,

what have you got on your bike? Top Case, loaded saddle paniers? Or this just you riding solo with no gear. What do you do when you load up?

[azkaisr]

I stopped in at pjh23bmw place tonight after work and we adjusted his suspension some to see if it clears it up. Hoping he gets a chance to ride the bike tomorrow and report on progress.

 

Kaisr

[pjh23bmw]

what have you got on your bike? Top Case, loaded saddle paniers? Or this just you riding solo with no gear. What do you do when you load up?

 

No top case, maybe approx. 5 lbs. in each panier. I weigh 202 with helmet, riding jacket, etc.

 

When checking it with Tom last night we noticed a lot of travel and bounce on the rear suspension so we tightened it up. Not sure what that will do. Will report backafter testing.

[zbassman]

I have a 2000 R1100RT and I've noticed a similar thing. It doesn't happen every ride, but it sure makes you pucker up when it does.

 

I have the side paniers and top case on. I am running brand new Metz Z4s. I'm running at 34/36 cold PSI.

 

I'm sort of a big guy, 6' 5" 315lbs. Do you think maybe I need to tighten up my rear suspension?

[Husker Red]

I was going to suggest checking the suspension too. At softer settings I notice more jiggling at speed too. Tighter her up and see what happens.

 

I also like higher tire pressures to keep her firm on the road, but it does make the ride rougher. I tend to run 38f 40r or even a bit higher.

[Husker Red]

I have a 2000 R1100RT and I've noticed a similar thing. It doesn't happen every ride, but it sure makes you pucker up when it does.

 

I have the side paniers and top case on. I am running brand new Metz Z4s. I'm running at 34/36 cold PSI.

 

I'm sort of a big guy, 6' 5" 315lbs. Do you think maybe I need to tighten up my rear suspension?

 

Definitely. You probably have to dial in some preload on the rear shock, plus IMHO I think you should be running higher pressures because of your weight.

 

In my previous post I was suggesting to tighten the rebound dampening using the screw near the bottom of the shock. I don't know if I was clear about that... You might need to do a bit of rebound adjusting too, but do one thing at a time.

 

Mike

[Edgar]

have the side paniers and top case on. I am running brand new Metz Z4s. I'm running at 34/36 cold PSI.

 

I'm sort of a big guy, 6' 5" 315lbs. Do you think maybe I need to tighten up my rear suspension?

 

 

At your size you need to increase your tire pressure before you do anything else.

[GregB]

Great input so far. I am running Bridgestones, and I'm not sure if that comes into play.

Mine with Bridgstone BT020 was awful on a grooved concrete freeway. I started thinking it was less stable than the R1100RT but finally realized it was great on rural asphalt roads, even at 110. Sold and stable with Avon Azaros, even at 120.

[pjh23bmw]

This is not really a tire pressure discussion. It's evolved to a suspension/tire/handling discussion. I started it so I guess I'll give you my input as to what we've done to improve handling.

 

I weigh ~200 lbs. in full gear. Panniers holding about 7 lbs. each.

 

Changed tire pressure from 38/42 to 36/40.

 

Dialed in the back suspension, both pre-load and shock. One of our contributors, Tom aka azkaisr, assisted me with this. With the factory recommended settings there was a lot of up-down travel on the rear shock when seated and bouncing on the bike. So we increased the pre-load and damping quite a bit (not all the way though). This change has improved the handling and control at speed significantly. I think we can tweak it a little more to get it even better.

 

Also, interested to know if anyone else has trouble with those Bridgestones and if the Avons are better.

 

Thanks for all the help.

[ShovelStrokeEd]

You don't need to tighten up your suspension, you need new suspension. Both spring rates (front and rear) are calibrated for a ~170 lb rider. No amount of preload is going to even get you in the ballpark.

 

Sorry, big guy, but your due for about a 12-1500 dollar upgrade and maybe more since, at your weight, you probably are going to need a custom rear spring.

 

The good news is that if you liked the bike before, you'll just LOVE it after the transformation.

[bross]

I've only had my 1200RT for two months and 4000 miles after 17 years of riding Kawasaki Voyagers but I haven't noticed any tendency for the RT to become "skittish" or "react to the slightest crosswind". Of course the Voyager with a full fairing doesn't provide any place for side winds to pass through either but it's also 200 pounds heavier than the RT. I'd say the RT is almost as stable in cross winds as the Voyager. BTW, I'm running Bridgestone BT020 tires.

I have to agree, I'm on my OEM Z6s and the RT is extremely stable at elevated speeds. It must be your road surface, we don't have any rain groves here just tons of chip seal which eats tires.

[ncsonderman]

 

Me too. I'm currently running my Z6's at 34/38 and the current set has 12749 miles on them. I think that's a personal record for any set of tires on my RT's including 1 set of Pilot Roads.

 

I check them every week for any sign of cords as the rear Z6 wear indicators are too far to the sides to be trusted. Most weeks I only ride about 250 miles so this should work out OK. Needless to say the replacement set is leaning against the HF tire changer.....

 

As to why? I can only speculate......

 

Stan

 

I'm on my third set of MEZ6's and run 33 front and 36 back. I can't seem to get over 7K on a set. I've got only 5500 on my current set and the front is shot!

 

What gives?

[bross]

I'm on my third set of MEZ6's and run 33 front and 36 back. I can't seem to get over 7K on a set. I've got only 5500 on my current set and the front is shot!

 

What gives?

16,000kms (9941mi) on mine and they still have a bit of life left, well the front does, I have no idea how much life is left in the rear. I ride aggressively but we have all straight roads around here so it's only on trips that I get to actually lean. Maybe they're a good droning tire?

 

Rear

 

Front

[Mike05]

Bross,

 

I may have missed it but what tire pressure are you running?

[Bob Palin]

I'm on my third set of MEZ6's and run 33 front and 36 back. I can't seem to get over 7K on a set. I've got only 5500 on my current set and the front is shot!

 

What gives?

Nothing, that seems pretty normal. You could experiment with tyre pressures since you are running at the low end of the range.

[zbassman]

As the eminent and perspicacious Homer J. Simpson might say: D'oh!

 

I was looking at Metzeler's website. I had been starting with the PSI recommendations on their website for the Z6s. But on another part of the site I read that this is the minimum PSI. They recommend trying to run as close to the max on the tire sidewall as possible.

 

I tried 38/36 today and it was better. I'll try 40/38 tomorrow see how that goes. After that I'll try adjusting the pre-load settings.

 

Someone suggested that at my size I really need a new suspension system. But a new suspension system is not in my immediate future, so I'll just need to find the best setting I can with what I got.

[marcopolo]

 

Me too. I'm currently running my Z6's at 34/38 and the current set has 12749 miles on them. I think that's a personal record for any set of tires on my RT's including 1 set of Pilot Roads.

 

I check them every week for any sign of cords as the rear Z6 wear indicators are too far to the sides to be trusted. Most weeks I only ride about 250 miles so this should work out OK. Needless to say the replacement set is leaning against the HF tire changer.....

 

As to why? I can only speculate......

 

Stan

 

I'm on my third set of MEZ6's and run 33 front and 36 back. I can't seem to get over 7K on a set. I've got only 5500 on my current set and the front is shot!

 

What gives?

 

On Metzeler's international website (under Fitment Chart), they recommend 36F/42R for the Z6s on an R12RT. They don't say what load that's for, however.

[Rusty1945]

On Metzeler's international website (under Fitment Chart), they recommend 36F/42R for the Z6s on an R12RT. They don't say what load that's for, however.

That sounds like the BMW recommendation for higher loads such as luggage/passenger. I'm wondering why folks feel the need to deviate from the BMW recommended pressures, assuming you're not, ah, an unusual weight

[AceVentura]

Ace,

what have you got on your bike? Top Case, loaded saddle paniers? Or this just you riding solo with no gear. What do you do when you load up?

 

Just me so far, on occation I have a few items in the side cases. I am about 235 lbs.

[bross]

Bross,

 

I may have missed it but what tire pressure are you running?

34/38, I'm 200lbs, no side cases unless on a trip, just my lunch in the tank bag. I've tried various pressures on my meanstreak through 4 sets of tires and like someone else said, I didn't see any increased mileage with running higher pressures, so now I just go with the manufacturers pressure +2 lbs. I'm anal about my tire pressure but frankly I've never found a low tire and usually just have to add a bit when it gets cold.

[Bob Palin]

I'm wondering why folks feel the need to deviate from the BMW recommended pressures

Because our priorities are different than BMW's. They are going for a combination of comfort and handling, some of us prefer to try and increase mileage at the cost of some comfort and handling.

[KDeline]

If we ran SLIGHTY higher pressure, wouldn't we get more tire life. I was thinking 44 front 48 rear?

[bross]

If we ran SLIGHTY higher pressure, wouldn't we get more tire life. I was thinking 44 front 48 rear?

That's what a lot of people believe, but personally my experience doesn't support it. I have been through 4 sets of tires on my meanstreak which granted is a cruiser, but is similar to the RT etc. in that it runs the same sport touring tires as I run on the RT, weighs 650lbs (more than the RT), and gets ridden aggressively, but obviously can't lean as far as the RT. I tried running Kawasaki's recommended pressures (36/36), running higher pressures (42/42), running a few pounds more (38/38), and am running the 4th set at 36/36. I have averaged 13-14,000kms from every set of tires and wear has been even each time as well. So for me I just add a few pounds to the manufacturers recommendations and that's what I run. Even the tire manufacturers suggest running what the bike manufacturer recommends.

 

The tires I ran on the meanstreak were:

Dunlop D220s

Bridgestone Battlax BT020s

Bridgestone Exedra 851/850s

Avon Azaro ST45/46s

 

And I'm at 16,000kms on the OEM Z6s on the RT. They have a bit left on them but I have a set of Conti Road Attacks ready to go on, so I'm quite happy running what BMW tells me to run.

[accounting]

I have a 2005 RT with 9700 miles on my Z6's. I do not use the side bags much. I am 185 lb. an run 32/37 PSI. I feel this is a great PSI for the way I run the bike. I should have many more miles on these tires.

CW

[Bob Palin]

If we ran SLIGHTY higher pressure, wouldn't we get more tire life. I was thinking 44 front 48 rear?

That doesn't exactly seem like a SLIGHT increase! What are the recommended pressures for your bike/tyre combination?

 

As for getting more miles by increasing pressure, it was a rock solid absolute increase of almost 50% for me, same bike, same tyres, same mixed route commute. I went from about 5K to 7-8K on MEZ4s on my RT. My ME880s have been quite variable but so has my riding since I started using them so I can't draw solid conclusions, besides, I haven't tried lowering the pressure with them I run 38f40r normally and 40/42 if really loaded down but I find that a bit harsh.

[tobyzusa]

 

I'm on my third set of MEZ6's and run 33 front and 36 back. I can't seem to get over 7K on a set. I've got only 5500 on my current set and the front is shot!

 

What gives?

 

Try puttin' some aerr in dem der tie-ares.