Tire Pressure with a Light Load

[vroomr]

On a lightly loaded bike, what tire pressures do you folks use and why? I use a pressure a little above the recommended minimum, to allow for the fact that tires always seep air.

My reasons for doing this are
- A highly inflated tire on a light bike will have a shrunken contact patch. Contact patch is my friend.
- Maybe BMW knows what they’re doing.

The potential for increased wear doesn’t enter my calculus.

When my bike is loaded I use the higher recommended pressures.

I’ve never met anyone who uses less pressure than the bike’s (any brand) recommended max regardless of the load, and in some cases even higher pressure, though on the R the rear tire’s absolute max is equal to BMW’s recommended max.

So, what inflation do you use with a light load, and why?

[deilenberger]

Exactly what BMW recommends, 32 front, 36 rear @70F.. and there is no need to go higher. I have a tire-pressure-monitoring system on my R (aftermarket), so I can keep an eye on pressures quite easily. Over about 3 months I haven't had to add air once.. pressure has stayed right on the numbers.

Oh - reason I mentioned "@70F" - the tire pressure monitoring system is really handy, and you'd be surprised the change in pressure with temperature. At 35F I see 30-31F, 34-35 R. My system also displays the tire air temperature, and sure enough - when the internal temp in the tire reaches 70F - the numbers are right where they are supposed to be.

I tried higher pressures - and it made the bike feel unstable and harsh riding. Didn't like it at all. The factory numbers seem to work.

[vroomr]

Thanks. My statement about everyone using max pressure is now inoperative!

[deilenberger]

I can't complain about tire longevity using the factory recommended pressure.. Even though I have a set of new PilotRoad2's sitting waiting for spring to throw them on, the current ones on the bike probably have about 3,000 miles left in them.. and they have about 10,000+ miles on them now. Looks like the PR2's are pretty happy with the factory pressure.

[Fisherman]

Exactly what BMW recommends, 32 front, 36 rear @70F.. and there is no need to go higher. I have a tire-pressure-monitoring system on my R (aftermarket), so I can keep an eye on pressures quite easily. Over about 3 months I haven't had to add air once.. pressure has stayed right on the numbers.

Oh - reason I mentioned "@70F" - the tire pressure monitoring system is really handy, and you'd be surprised the change in pressure with temperature. At 35F I see 30-31F, 34-35 R. My system also displays the tire air temperature, and sure enough - when the internal temp in the tire reaches 70F - the numbers are right where they are supposed to be.

I tried higher pressures - and it made the bike feel unstable and harsh riding. Didn't like it at all. The factory numbers seem to
work.

With all due respect are you recommending disregarding the tire manufacturers numbers? Just asking....

[deilenberger]

With all due respect are you recommending disregarding the tire manufacturers numbers? Just asking....

The numbers on the sides of the tires are the MAXIMUM inflation numbers, packed down for two weeks of camping with a fat babe(tm) on the back.. (they're actually the max inflation pressure that is SAFE to use - not the recommended inflation pressure.)

So - the answer is - yes, but it depends. IF the manufacturer has a table of suggested inflation pressures given for (1) MY bike (2) different loads (3) riding conditions (4) temperatures [and yes - that does make a difference] - then I might try them.

So far - Michelin says "Follow manufacturer's recommended inflation pressure.."

Here is their page for PR2's: http://www.michelinmotorcycle.com/index ... PilotRoad2

And here is their page for maintenance: http://www.michelinmotorcycle.com/index.cfm?event=404 (Under Construction)..

Had to go to the Ireland site to find any mention of inflation:

http://www.michelin.co.uk/michelinuk/en ... 13000.html

"INFLATION

Correct inflation is essential to the tyres' safety, comfort and durability. Maintaining the bike manufacturer's recommended inflation pressures has a positive effect on handling characteristics. It is also a major influence on the motorcycle's handling, both in a straight line and when cornering, even at moderate speeds and under braking.

Riding on underinflated tyres can cause premature wear, irreversible damage to the casing and, possibly, a catastrophic deflation.Tyres lose air gradually. It is essential to check pressure every 2 weeks, when the tyres are cold. If the pressure is checked during or after a ride, the tyres will be hot, which will increase the indicated pressure. Never deflate tyres when they are hot. If the pressure reading is lower than the recommended pressure, air must be added to the tyre. Keep in mind that the indicated pressure of a hot tyre can be as much as 4psi higher than the recommended cold pressure."

So to some extent - I'm following the tire manufacturer's recommendations - which is to follow BMW's recommended pressures. All makes sense eh?

Best,

[deilenberger]

Fisherman (dunno your real name)..

That got me looking, and I seem to recall Metzler at one point having some tire pressure tables, so I went looking. They are located at:

http://www.us.metzelermoto.com/web/prod ... fault.page

It says before the table:

"Always inflate tires to the correct pressure as indicated in the owner's manual. However Metzeler North America has found the air pressure suggestions listed below will improve mileage and customer satisfaction especially if a emphasis is placed on running the air pressure towards the maximum as stated on the sidewall."

So - in looking at the table (which I find interesting in they lump radial and bais tires together.. rather unexpected to me..), what is interesting is - the low end of the recommended solo pressures is almost identical to BMW's recommendation of 32F/36R - Metzler suggests 34F/36R. Not a lot of difference.

I then waffled over to Avon in the UK: http://www.avon-tyres.co.uk/motorcycle/ ... your-tyres, who sez:

"Pressures up to scratch? Maintaining the correct tyre pressures is critical to your safety, so never think, ‘oh, they’ll do’. Check in your handbook (or with your local Avon dealer) to see what’s right for the speeds you’ll be riding at and the load you’ll be carrying...

... Correct pressures – Your tyre is designed to perform perfectly at a very specific pressure. Inflated correctly, it provides the optimum contact patch for superb roadholding and water dispersal, as well as giving good handling, comfort and lifespan characteristics."

I couldn't find any other pressure recommendations on their website, so I'm guessing the "handbook" is the bikes owners manual. Could be wrong on that - but Avon tires I've owned never came with their own handbook.

Next I went poking around for Conti.. the German mototyre website is broken - when I went to Tire Safety - none of the links worked, so off to the UK one (there is no US one..)

That site has a rather long dissertation on tyre pressure: http://www.conti-bike.co.uk/default.asp?pid=27

"Advice on tyre pressure
Motorcycle manufacturers always go into the subject of air pressure in great detail in their vehicle manuals. It is possible to find instruction on air pressure for every driving situation. In addition it is usually possible to find a sticker on the vehicle with the necessary information written on it.

The manufacturers make a distinction between load (riding solo or with a pillion passenger, with or without luggage) and speed (on secondary roads or motor-ways).

Naturally in such a short fitment guide it is not possible to give the necessary tyre pressure details for every motorbike and because of this we refer you to the recommendations of the motorcycle manufacturers.

From years of experience we are aware that motorcyclists sometimes ride on tyres for which the air pressure is not suited to the driving conditions. We do however advise that you always ride at the highest pressure level given in the manual.

Some amount of comfort will be lost, but that loss will be outweighed by improved safety. In addition the rolling resistance will be lower which will help to save fuel.

Incorrect inflation pressure reduces the service life and may have a negative influence on the riding characteristics of the motorcycle.

Under-inflated tyres flex excessively, easily overheat and can suffer damage. Over-inflation can cause uneven wear. Improper inflation, either too high or too low, can adversely affect overall handling and ride quality.

Tyre pressure will be measured when the tyres are cold. During riding the tyre becomes warm and the tyre pressure is there-fore higher (up to 0,5 bar). This excess pressure should not be let off as it will automatically be balanced out as the tyre cools down again.

If you possess no tyre pressure recommendations for your motorcycle follow air pressure recommendations shown in the Continental fitment guide.

As a rule the tyre pressure for motorway riding should be 0.2 bar higher. The same also applies to a bike with a fully laden rear axle."

So - there we are again. They refer you to the owners manual. But being curious - I thought I'd see if they have a table of recommended pressures for the R1200R - and they DO! : http://www.conti-bike.co.uk/bikemodels. ... ikeid=3275

They are recommending 2.5bar (36PSI) front, and 2.9bar (42PSI) rear. Problem I see - it has no adjustment for the load on the bike or speed, so I'd assume these are the max pressures suggested (ie - fat-lady on back, going camping for 2 weeks.. going down a motorway for hours at 100MPH..) From memory (bike isn't in front of me - nor is the owners handbook) - those are the same pressures BMW gives for fat-lady/camping/high-speed use.

IMHO (and that's ALL it is) if mileage is all important - then you may maximize it by running at the higher recommended pressure (such as what Conti suggests). Downside is for sure a loss of comfort. Since I'm getting bored with the Michelin PilotRoad2's before they are worn out (mine have about 11-12k miles on them now and they still aren't worn out) mileage isn't a big concern for me. I'll run mine where I find them comfortable and where they feel safe. When I tried higher pressures - not only was it uncomfortable - it also felt as if I was loosing some grip from the tires. Might have been my imagination, but I don't think it was..

Truely a case of "YMMV"..

Good luck!

[Mort]

The OE Conti Road Attacks on my UK bike didn't last long at all - I only got 2500 from the rear before it 'squared off'. The bike then failed it's MOT because the front had worn (but just on the right side ?) & needed replacing at just over 3000 miles! I do ride quite hard but I thought that was pretty bad.

Unfortunately I'd replaced the rear with a Conti (to match the front which I thought would give me at least 5000 miles) so I had to put another Conti on the front to get through the MOT.

[deilenberger]

The OE Conti Road Attacks on my UK bike didn't last long at all - I only got 2500 from the rear before it 'squared off'. The bike then failed it's MOT because the front had worn (but just on the right side ?) & needed replacing at just over 3000 miles! I do ride quite hard but I thought that was pretty bad.

Unfortunately I'd replaced the rear with a Conti (to match the front which I thought would give me at least 5000 miles) so I had to put another Conti on the front to get through the MOT.

Must be quite an agressive rider - I went through Conti RA's about every 6k miles.. which is why I'm delighted with the wear on the Michelins. All were run at recommended pressure.

[Fisherman]

Hey Don,

It's "Fisherman" here. My real name is Walker Horsley and I live in Atlanta.
I can't explain it, but on my old 1200 GS and now my 08 RR the local dealer always inflates to 36/42.
In fact, I'm going in tomorrow for new rubber and I'll ask him why.

Thanks for all the great information you provide for this board.

[deilenberger]

Hey Don,

It's "Fisherman" here. My real name is Walker Horsley and I live in Atlanta.

Hi Walker.. you might want to create a "SIG" that has your name in it. Most people on this forum do, and are on a first name basis. I've found that makes for a really friendly forum. Anyway..

I can't explain it, but on my old 1200 GS and now my 08 RR the local dealer always inflates to 36/42.
In fact, I'm going in tomorrow for new rubber and I'll ask him why.

I'd be willing to bet that he has no documentation for doing it - but he feels safer putting the tires at near max inflation just in case someone grossly overloads thier bike. That gives him a liability "out" if they then have a tire failure when overloaded.

It's probably not a bad idea IF the rider doesn't adjust pressure for different loads. Since I have a tire-pressure-monitoring system on my R12R - I tend to be fairly fanatical about matching pressure/conditions.. and that's a different case then the average rider who rarely even thinks about tire pressure.

Thanks for all the great information you provide for this board.

I think it's a case of keyboard diarrhea sometimes..

[Fisherman]

Don,

I had new tires put on Friday and the dealer showed me the BMW recommended pressures for a loaded bike. (without a passenger) They recommend 36/42.

Walker Horsley

[deilenberger]

Don,

I had new tires put on Friday and the dealer showed me the BMW recommended pressures for a loaded bike. (without a passenger) They recommend 36/42.

Walker Horsley

Walker - he's correct - and if you note - I said pressure should be adjusted for load AND speed. And that the info is right on a tag under your tank.

FWIW - the original question was: "So, what inflation do you use with a light load, and why?" and that's the question I answered. Ask me about a loaded bike, and you'll get a different answer. I try to be precise and answer what's asked.

Best,

[thepeacebullgrunt]

Interesting conversation...

My tires are Michelin Pilot Road II
I am asking to Don or anyone else
Do you still recommend me to follow BMW recommendation or to increase few PSI...
and how much ?

Is there a way to estimate how much should be the right pressure
according to the ambient temperature
starting from the time I stopped the bike ?
(I have a convenient cycle pump with a plug that I installed under my seat)

Just like an idiot, every 2 weeks or so at a +/- 9am Californian morning ambient temperature...I am putting 42 PSI in my cold tires in front and rear, indeed I feel like my bike is acting weird sometimes... but must confess that my shocks are quite exhausted now at 25K so ! Ignorant as I am I think I was kind of trying to compensate my poor shocks by making my tires harder.

Rear Givi maxia -> 52 liters
RKA Side luggage -> 50 litters
Euro-Sport Jumbo Hauler by roadgear -> 50 Liters
and on top of the previously cited
another Euro-Sport Hauler again by Roadgear but smaller -> 28 Liters.

These are my loads which in normal days are lightly loaded... which mean 1 Laptop, 1 Extra helmet, One rain cover, One cycle pump, One quart of oil, One light tools box.