R100S Tire Pressures?

[Major Softie]

What about the % rule (I forget what % is used).

But you start with cold tires, at your best guess. Go for a long ride and warm them up. Stop and check the pressure when they are warm. If they show too much pressure increase, I believe that means the tire pressure was too low to begin with. (Tire flexing causes heat that causes air pressure to rise.)

If your pressure check shows no increase in pressure, they were probably too high to begin with.

All, feel free to critique my logic.

I don't think anything is wrong with your logic, but your recommendation has a rather large hole in it. Exactly what is "too much pressure rise?" That is the crux of your recommendation.

[Deleted User 287]

I don't think anything is wrong with your logic, but your recommendation has a rather large hole in it. Exactly what is "too much pressure rise?" That is the crux of your recommendation.

Tire pressures go up 10-15% when they're warm, so if you started at 36 and rode for 20 minutes, they will probably be between 38 and 40 PSI. You'll need to add or lower the pressure from that pressure, and not from the original 36!

The entire article here:
http://en.allexperts.com/q/Motorcycle-S ... ssures.htm

Sorry Major, I am playing the flu card...

But I couldn't fall asleep, so I thought I would find someone on the internet to argue with.

[Phil_J]

On the Metzeler site they state 2.1 bar front 2.3 rear. I would start there and fine tune up or down if there was an improvement

Phil

[Roy Gavin]

I use 32/34 f/r with contemporary road tires on my road bikes, stable but a bit harsh.

With 80/20 soft road tires like Avon Distanzas ,Scorpions, and old tech tires like Dunlop TT100's or Barum (Mitas) E07s a bit less is OK, 26/28 works OK on and off road , and it seems to suit the suspension better, remember it was designed to work with old low tech, low pressure tires.

I usually do a fingertip check of tire temp after a run, anything more than slightly warm and I increase the pressure - road tires dont need much, if any, heat in them to give full grip.

What is surprising is just how well the 40 year old low tech tires work - the TT100s now have a modern compound and stick and work as well as just about anything on the road, and the Barums are the best tire I have had on the G/S combining grip , comfort, handling and extra long life better than any other tire I have tried.

[richard t]

Thank you, but I'll keep doing that. I've used the factory psi my entire life....on my cycle tires, car, truck, wheel barrow, what ever. Up to and with in a few psi. The factory psi on the sidewall is perfect info Major for what to run, as it always says to "Never exceed". Otherwise, wouldn't you say one is just guessing.

Edit to add...seems most all cycle tires have a never exceed of 40 psi front and back, as far as I recall.

I'm sorry dwerbil, but you are quite simply incorrect. If you trust the manufacturers so much (a perfectly reasonable trust), then just check their sites, and they will inform you as to your error.

In addition, may I correct my earlier statement about it being the maximum pressure for the tire. That was incorrect as well. I believe there was a time when tires showed max. inflation (as bicycles still do), but that is definitely not the case now. Now, the pressure on the side of the tire is the pressure at which their maximum load rating has been tested. If I may reference the Avon Motorcycle Tires "Tires 101 for Consumers" .pdf document:

A tire inflation pressure is on the sidewall of every tire showing a tested pressure under load. This is neither the recommended pressure nor the max inflation.
http://www.avonmoto.com/download/Tires1 ... sumers.pdf

In other words, the only thing the pressure on the sidewall tells you today is that this is the pressure at which the tire was tested in reference to its maximum load rating.


On your second point (in your edit) exactly zero of the 8 mounted motorcycle tires in my possession list 40 lbs as their max load rated psi.

the Avon article has been out a while and is good info. I run less air in LaDonna's tires than mine because her bike carrys on 1/2 the weight mine carrys. I do have some non-bike tires that say don't exceed or max pressure on the side wall.

[Deleted User 62]

I check my tire pressures regularly, but when I took it to be inspected last time, the guy said my front tire showed signs of having been "way under inflated for a long long time". He pointed out that the outer two thirds were worn out, while the center one third of the tread was not. I took this with a grain of salt considering; 1: I always check my tire pressures, 2: I ride hard and lean over in the twisties, 3: Bridgestone Spitfires are supposedly a harder compound in the center for longer life, and lastly, 4: he was working at a Harley dealership, and likely never saw tires that had been leaned in a turn... What do you think? Should I be running higher pressures than 32 front 34 rear??

[ME 109]

What do you think? Should I be running higher pressures than 32 front 34 rear??

For me those pressures would be a minimum, but a maximum being only two - three psi more. Generally speaking.

[montmil]

I check my tire pressures regularly, but when I took it to be inspected last time, the guy said my front tire showed signs of having been "way under inflated for a long long time". He pointed out that the outer two thirds were worn out, while the center one third of the tread was not. I took this with a grain of salt considering; 1: I always check my tire pressures, 2: I ride hard and lean over in the twisties, 3: Bridgestone Spitfires are supposedly a harder compound in the center for longer life, and lastly, 4: he was working at a Harley dealership, and likely never saw tires that had been leaned in a turn... What do you think? Should I be running higher pressures than 32 front 34 rear??

Tim, I run Bridgestone S-11 Spitfires on my '81 R65 and have long since worn off the chicken strips. I maintain 32 psi in the Spitfire front tire and the same pressure in the Avon 404 front mounted on my '83 R65. My suggestion is to keep on keepin' on. We have a winner and it's #4!

And to all whom responded to my tire pressure question, please accept my sincere thanks. I appreciate all the viewpoints offered and have added a printed copy of this thread to my Luddite BMW 3-ringer. A Texas-sized Grande Muchas Gracias to y'all. I'm going to air up the R100S with 32F and 36R in the Metzelers as a starting point. Monte

[Duane Ausherman]

I check my tire pressures regularly, but when I took it to be inspected last time, the guy said my front tire showed signs of having been "way under inflated for a long long time". He pointed out that the outer two thirds were worn out, while the center one third of the tread was not. I took this with a grain of salt considering; 1: I always check my tire pressures, 2: I ride hard and lean over in the twisties, 3: Bridgestone Spitfires are supposedly a harder compound in the center for longer life, and lastly, 4: he was working at a Harley dealership, and likely never saw tires that had been leaned in a turn... What do you think? Should I be running higher pressures than 32 front 34 rear??

Tim, you are right in all 4 of your points. #4 was being kind.

[Seth]

I've searched both the Michelin and Bridgestone web sites and looked for recommended tire pressures and can't find any.
Where does the "Modern tyres seem to require higher pressures" info come from? I've heard it before, but can't find an official recommendation. Is it just another urban myth? I've used OEM recommended pressures on my BMWs and Triumph for years, now with the Michelin Pilot Activ with no issues.

Thx.