Good post....it amazes me at how many people think the pressure shown on the sidewall is the one to go by, both on cars and bikes.

 

I mostly go by the label on the bike or slightly less than the sidewall pressure. Works good for me anyway.

 

Good post....it amazes me at how many people think the pressure shown on the sidewall is the one to go by, both on cars and bikes.

The pressure printed on the tire, is the maximum pressure to be used when you are loading your vehicle to the maximum load range of the tire, which is also printed on the sidewall right before the max pressure listing, ie: xxx lbs @ xx psi.

On my Meanie rear tire (170/60R17) the max load is 783 lbs @ 42psi cold.
I run my rear tire pressure @ 40psi cold. A little rough on some roads, but it handles better for me.

 

Logic must escape you . What would someone writing an owners manual know about a tire made 30 years later ? Who knows more about the operating parameters of a tire , someone that designed a motorcycle 30 years ago or someone that manufactured a tire last year ?

I get this "garbage" not just from the side wall of the tire but from years of observing tire wear . My opinion is based on near thirty years of maintenance and service of motorcycles and accessories , Take it or leave it .

~kop

 

I'd say you're missing a bit of logic yourself.
You do realize that you're saying that load has no effect on required tire pressure?

Who knows more about the operating parameters of a tire , someone that designed a motorcycle 30 years ago or someone that manufactured a tire last year ?

Not sure what you're getting at there, I quoted the actual tire manufacturers in my first post. But you're claiming to know more than the actual tire manufacturers.

And I have you beat by at least ten years experience, plus schooling provided by Goodyear.

Your opinion doesn't impress me, aside from being wrong.

 

Here's what Dunlop has to say. Tire Tips

"Overinflating tires does not increase load carrying capacity, but will result in a hard ride and accelerated tire wear in the center of the contact patch."

Nowhere in the document does it say that inflation to the sidewall pressure, rather than MOM pressure, constitutes overinflation.

The sidewall DOES however, state, for example, "Max load 908lbs @ 40psi cold"
The load rating IS impacted by inflation level, and that 77H tire may only be a 74S at 32psi

This statement is supported in the reference:
"Keep in mind that hard cornering, passengers, heavy loads and sustained high speeds will require higher pressures (up to that indicated on the sidewall)."


Both the sidewall load rating AND pressure are max, and exceeding either or both can cause tire failure.

You have NEVER seen anyone on this forum recommend operating tires in excess of sidewall inflation limits.

Furthermore:
"For high-speed, fully loaded or dual-riding touring motorcycle applications, inflate front tires to maximum recommended by vehicle manufacturer for Dunlop fitment and rear tires to maximum load inflation pressure on sidewall. Rear touring tires must be inflated to a minimum of 36 psi for light to medium loads and 40 psi for dual riding and other loads. Never exceed maximum load indicated on tire sidewall or vehicle capacity load found in owner's manual."

One again... MINIMUM 36psi for light to medium and 40psi for 2-up.
The 2006 Vulcan 1600 Nomad MOM indicates 28psi front, 36psi rear.

Your comment "may get someone hurt" is completely off-base. In fact, running 2-up on an underinflated tire may result in tread separation.

And Bridgestone: AdditionalInformation

"Always keep the motorcycle manufacturer's recommended air pressure in both tires. This is an important requirement for tire safety and mileage. Your motorcycle owner’s manual will tell you the recommended cold inflation pressure. The pressures stamped on the sidewall of the tire are only for maximum loads. On some occasions, these pressures will also be the manufacturers recommended settings as well."

And Pirelli: PIRELLI - Tyre Pressure

"Over-inflation or extreme tire pressure will impair your riding comfort and decrease the contact of the tire with the road. The manufacturer's information is the minimum values only. With luggage or with a second rider the rear tire needs an extra 0.2 bar, and for high speed riding the pressure of the front tire should also be increased by 0.2 bar."

And Metzeler: METZELER - Maintenance

"Increase rear tyre pressure by 0,2 bar / 3 psi when riding with a passenger or with very heavy load. Insufficient inflation pressure causes tyre flexing and overheating that may lead to internal damage. Overinflation impairs riding comfort and stability and can result in uneven wear."


Also, take into account that different tire types from even one manufacturer may have different recommended maximum inflation pressures. Example, some Avon Venom series with reinforced sidewall carry a max inflation of as high as 47psi. The reinforced sidewall combines with the higher pressure to increase the load rating of the tire.
Should this tire be run at the same pressure as a tire that carries a manufacturer's max of 42psi?

I think that ought to be enough to make my point, and that is "Anyone telling you to always inflate your tires to the max pressure printed on the sidewall is wrong", always follow the info in the owners manual.

Completely wrong.

Anyone telling you to inflate ABOVE the max pressure indicated on the sidewall is dangerously wrong. As indicated by Pirelli and Dunlop, MOM is a minimum, the sidewall is a maximum.
If you CALL Metz and ask what is recommended for a Vulcan 1600 with their 180/70R-16, they will tell you 42psi.

Furthermore, Navy testing at Pax river show a direct correlation between tire pressure and the speed at which hydroplaning will occur. I don't recall the exact formula, but a typical passenger car tire at 28psi will begin to hydroplane at 55mph. The same tire and road conditions at 36psi moves that speed up to 70mph.

I have ALWAYS run max sidewall inflation levels on my cages unless airing down for off-road use, and I have never experienced uneven treadwear.... but I have been able to get 60,000 miles out of a cheap set of Sears tires that were rated for 40,000 miles.

 

I run my GS1100, and my GPz1100 tire pressures accorging to my weight (I only weigh 155 lbs) , and my handling preference. I feel most comfortable right around 28 psi... seems to be a good compramise between, good cornering grip and feel, and good bump absorption cornering on bumpy, cracked pavement..

I could care less what the owner's manuall states for recommended pressures. I like my pressures a little on the soft side for better feel. I am also giving up some tire longevity on the downside, but this is my preference...

I start getting above 35 psi, and I start to feel the front end skip around cornering through the bumpy stuff a bit too much...

 

"Overinflating tires does not increase load carrying capacity, but will result in a hard ride and accelerated tire wear in the center of the contact patch."

Nowhere in the document does it say that inflation to the sidewall pressure, rather than MOM pressure, constitutes overinflation.

The sidewall DOES however, state, for example, "Max load 908lbs @ 40psi cold"
The load rating IS impacted by inflation level, and that 77H tire may only be a 74S at 32psi

Amazing, sure seems like I was right according to what you just said, but somehow you think I'm wrong?

I didn't say anything about overinflation, did I?
And didn't I just mention that air pressure affects load rating?

This statement is supported in the reference:
"Keep in mind that hard cornering, passengers, heavy loads and sustained high speeds will require higher pressures (up to that indicated on the sidewall)."


Both the sidewall load rating AND pressure are max, and exceeding either or both can cause tire failure.

You have NEVER seen anyone on this forum recommend operating tires in excess of sidewall inflation limits.

Where are you getting this stuff from? Where did I say anything about someone recommending that max pressure be exceeded??

Furthermore:
"For high-speed, fully loaded or dual-riding touring motorcycle applications, inflate front tires to maximum recommended by vehicle manufacturer for Dunlop fitment and rear tires to maximum load inflation pressure on sidewall. Rear touring tires must be inflated to a minimum of 36 psi for light to medium loads and 40 psi for dual riding and other loads. Never exceed maximum load indicated on tire sidewall or vehicle capacity load found in owner's manual."

One again... MINIMUM 36psi for light to medium and 40psi for 2-up.
The 2006 Vulcan 1600 Nomad MOM indicates 28psi front, 36psi rear.

And again, where did I say anything contrary to what you write above?

Your comment "may get someone hurt" is completely off-base. In fact, running 2-up on an underinflated tire may result in tread separation.

I'd say my comment was exactly on base, nowhere did I recommend any particular air pressure, I merely recommended exactly what the manufacturers say.

By the way, when a tire has a max load limit of 400 lbs at 42 psi, what happens to the contact patch when that tire has a 200 pound load and you air it to 42psi? It reduces the contact patch, and you bend it into a turn on that reduced contact patch, and you lowside it.

"Always keep the motorcycle manufacturer's recommended air pressure in both tires. This is an important requirement for tire safety and mileage. Your motorcycle owner’s manual will tell you the recommended cold inflation pressure. The pressures stamped on the sidewall of the tire are only for maximum loads. On some occasions, these pressures will also be the manufacturers recommended settings as well."

"Over-inflation or extreme tire pressure will impair your riding comfort and decrease the contact of the tire with the road. The manufacturer's information is the minimum values only. With luggage or with a second rider the rear tire needs an extra 0.2 bar, and for high speed riding the pressure of the front tire should also be increased by 0.2 bar."

"Increase rear tyre pressure by 0,2 bar / 3 psi when riding with a passenger or with very heavy load. Insufficient inflation pressure causes tyre flexing and overheating that may lead to internal damage. Overinflation impairs riding comfort and stability and can result in uneven wear."


Also, take into account that different tire types from even one manufacturer may have different recommended maximum inflation pressures. Example, some Avon Venom series with reinforced sidewall carry a max inflation of as high as 47psi. The reinforced sidewall combines with the higher pressure to increase the load rating of the tire.
Should this tire be run at the same pressure as a tire that carries a manufacturer's max of 42psi?

Completely wrong.

Anyone telling you to inflate ABOVE the max pressure indicated on the sidewall is dangerously wrong. As indicated by Pirelli and Dunlop, MOM is a minimum, the sidewall is a maximum.
If you CALL Metz and ask what is recommended for a Vulcan 1600 with their 180/70R-16, they will tell you 42psi.

Furthermore, Navy testing at Pax river show a direct correlation between tire pressure and the speed at which hydroplaning will occur. I don't recall the exact formula, but a typical passenger car tire at 28psi will begin to hydroplane at 55mph. The same tire and road conditions at 36psi moves that speed up to 70mph.

I have ALWAYS run max sidewall inflation levels on my cages unless airing down for off-road use, and I have never experienced uneven treadwear.... but I have been able to get 60,000 miles out of a cheap set of Sears tires that were rated for 40,000 miles.

You get an A+ for disagreeing with things I didn't say.

You really ought to read what was written before disagreeing with it, then you might have noticed (and saved yourself from looking silly) that nowhere did I say to "never" air the tires up to the maximum on the sidewall.

I said it's wrong to tell "everyone" that "regardless of the bike they ride", they "must air the tires to the maximum on the sidewall".

And if you are going to tell everyone that if they don't run their tires at the max pressure printed on the sidewall then they are under inflating their tires, then you're as wrong as that other dude.

 

I run my GS1100, and my GPz1100 tire pressures accorging to my weight (I only weigh 155 lbs) , and my handling preference. I feel most comfortable right around 28 psi... seems to be a good compramise between, good cornering grip and feel, and good bump absorption cornering on bumpy, cracked pavement..

I could care less what the owner's manuall states for recommended pressures. I like my pressures a little on the soft side for better feel. I am also giving up some tire longevity on the downside, but this is my preference...

I start getting above 35 psi, and I start to feel the front end skip around cornering through the bumpy stuff a bit too much...

You and I have nothing to argue about, I do the same thing, but I use the recommended pressures for a starting point.


You know what happens when you run your front tire at 28 psi because it works best, then a helpful relative airs it up to the sidewall maximum of 40 psi, then you bend it into a turn at your usual pace?
The front tire washes out and you lowside.

It takes awhile for cracked ribs to heal

 

Where are you getting this stuff from? Where did I say anything about someone recommending that max pressure be exceeded??

I "got that stuff" directly from the links that you posted and added quotes and bold for emphasis.

You stated "Anyone telling you to always inflate your tires to the max pressure printed on the sidewall is wrong" and you also said "and may get someone hurt"

That is incorrect according to everything that you linked from the tire manufacturer's sites.


So I assumed that since you actually read and comprehended the information posted on the manufacturers sites, that you must be referring to people recommending "overinflation" and not simply inflation to the max rating... which is perfectly fine according to the manufacturers.

Note that it's not JUST heavy passenger loads, but also for high speed riding and hard cornering that they recommend bumping inflation by 3psi or to no higher than the max permitted.



Nobody is "going to get hurt" running their tires at the sidewall pressure.
Will the ride be a little more harsh? Sure... but it's a motorcycle, not a Rolls Royce. Will the tires last longer? Absolutely.

 

one of the problems I see with using the owners manual as a reference point is the assumption on their part that the average rider is 150 lbs. I weighed 151 when I graduated High School. My experience with the average weight of the riders I come across is that they weigh much more than the 150 lbs. the manual assumes is average!! If you use the 150 lb. reference and you weigh 50 lbs. more and add another rider (wife) who weighs lets say 150 lbs. (it was their number), then the pressure in the manual is, lets say a long, long, way off the mark.

I would bet that there are many people riding bikes that according to the manual are overloaded. If they fail to make an adjustment to tyre pressure that could be hazardous to your health. BUT, because manuals are written to basically CYA, they leave plenty of room between the 150 lb. average rider pressure and the Max load pressure on the sidewalls. If you weigh nothing to 150 lbs. then use the manual and make sure you don't haul much. Otherwise, put some air in there (up to the max load pressure ratings on the sidewall).

My 2 cents~~
I keep mine toward the upper end of the pressure, maybe it's different for sport bikers?

Ride Safe-----------------------

 

I "got that stuff" directly from the links that you posted and added quotes and bold for emphasis.

You stated "Anyone telling you to always inflate your tires to the max pressure printed on the sidewall is wrong" and you also said "and may get someone hurt"

That is incorrect according to everything that you linked from the tire manufacturer's sites.

So, you're saying that the tire manufactures state to "always" inflate your tires to the maximum on the sidewall?

You did see that word "always" in there, right??

Are you just wanting to argue or something?

I'll say it again:

Nowhere do I say or imply that you should "NEVER" inflate to the max pressure listed on the sidewalls, I said that the person saying your tires are under inflated if not inflated to the sidewall max pressure all the time was wrong. You may post quotes and links without reading them, but I don't, and every one of those quotes and links support my position.

Your arguments are not making any sense.


Edit:

Using the Owners Manual as a starting reference is wrong? You have to start somewhere reasonable, and my Kawasaki Owners manuals tell you what pressure to run with specific rider weights, so that seems a reasonable reference to me.

IIRC, it says for riders less than 200 pounds use x pressure, and for riders over 200 pounds use Y pressure, and for high speeds, or two up riding, inflate the tires an addition z psi.
The recommended air pressures on mine are under the seat, but it's a pain to get there cause I have soft luggage mounted.

 

Whatever. There's no point in carrying this on further.


Nobody is going to get hurt running max inflation 24/7, which is what you said, and it's wrong.

 

amazing ...

~kop

 

Yup.... all of that over 4psi.


How far off are typical gauges? Accu-Gauge 0-60psi gauge is calibrated to 1psi @ 30psi and accurate to +/-1.2psi from 15-45psi.

The cheap auto parts store "stick" gauges and gas station gauges? No telling.

 

Yup.... all of that over 4psi.


How far off are typical gauges? Accu-Gauge 0-60psi gauge is calibrated to 1psi @ 30psi and accurate to +/-1.2psi from 15-45psi.

The cheap auto parts store "stick" gauges and gas station gauges? No telling.

I have 5 tire gauges - two stick types, one dial type, one digital and one dial type on the inflation tool that came with my compressor.....not one of them reads the same.....so, as I would rather be running a few pounds high than low. I choose the one that reads the lowest and inflate the tire according to that one based on what the owners manual for the bike recommends for specified riding conditions....the exception being the KZ....it gets 4 psi more than OM recommends as I have found the tires wear better running that PSI.

 

I don't use stupid tire gauges. Gauges are for nerds. I use my ear.... I poke the air valve with a sharp object, and if I hear some air leaking i've got about 25 psi in the tire, if I hear a LOT of air exiting the valve, I have about 40 psi...

I have much more usefull things to spend my money on, (like duct tape, and zip ties)

 

I don't use stupid tire gauges. Gauges are for nerds. I use my ear.... I poke the air valve with a sharp object, and if I hear some air leaking i've got about 25 psi in the tire, if I hear a LOT of air exiting the valve, I have about 40 psi...

I have much more usefull things to spend my money on, (like duct tape, and zip ties)

I'll continue to be a nerd.

 

That is an amazing post. very informative. but I need a new tire gauge though...Can you donate one? just kidding....

 

I always learned, check pressure cold, then hot, diff of 2-3 psig is optimum, of course now i need to follow that up, as I am running nitrogen in my tires

 

I always learned, check pressure cold, then hot, diff of 2-3 psig is optimum, of course now i need to follow that up, as I am running nitrogen in my tires

I guess I have to ask, what exactly is the reasoning for "cold" vs. "hot" tire temps, and furthermore what is the reason for running expensive nitrogen in a street driven motorcycle??????

 

I guess I have to ask, what exactly is the reasoning for "cold" vs. "hot" tire temps

Gas expands when heated, so checking the tires "hot" results in both underinflation, and inconsistent inflation because you can never be sure exactly how hot the tire is.

I mean... you could fill them to <whatever> cold, then use an infrared thermometer to check pressure at various temperatures then graph it so if you air up on the road, you always know where you want to be... but that's a lot of work when it's easy enough to fill them cold.

what is the reason for running expensive nitrogen in a street driven motorcycle??????

Because PT Barnum was right.

There's no reason NOT to use it if it's free. To pay for it on any street vehicle is a waste of money. Air is already 78% nitrogen. Dumping the tire to "0" psi and refilling with pure nitrogen will still result in an oxygen content of around 7% at 40psi. You would have to fill and purge the tire 5-6 times to get the O2 content to under 3%.

Nitrogen is used in military and commercial aircraft for a number of reasons... the SR71 tires are pressurized to 600psi, but on any aircraft, a blown tire inside the wheelwell poses a serious risk of fire as both hydraulic lines, fuel lines, and electrical harnesses pass through the area. If the tire blows after retraction, the nitrogen content of the tire could be enough to prevent combustion in the confined area until the pilot can get the gear back down and make plans to return to the airport.

 

Then again, running hydrogen would reduce the unsprung weight...

 

Then again, running hydrogen would reduce the unsprung weight...

Less than you would think.

Back in the 70s, an NFL team was accused of using helium to allow longer kicks, but no helium was found when the opposing team tested the balls.

It was speculated over the next 20 years that there is actually very little difference in weight between a football filled with helium and "air" because of the greater mass of gas required to obtain regulation "x" psi.... which is not accurate, the helium football is 7grams lighter than the "air" ball and 1% lighter than an empty ball.
It was also speculated that because of the compressibility characteristics of helium, kick distances would actually be reduced.

Mythbusters went after it too.
Annotated Mythbusters: Episode 47: Catching a Bullet with Your Teeth and Helium Footballs
Busted :lol:


In a scuba tank, a 120cf tank filled to 3500psi with air comes in at around 45-50 pounds. The "air" weighs 10 pounds.
The same tank filled with high-helium trimix comes in at around 40-45lbs... the gas weighs about 5lbs.

 

Well, I guess I could see all of this as advantageous for your local Sunday closed course club racing.
But like I commented, with respect to a street driven motorcycle, you factor in all the negitive road surface variables one faces on the street every day, including limited top speeds and all of this is just seems a waste of time IMO. I'll stick with my tried and true Craftsman compressed air at 28 psi cold.... never gone down after 23 years....

Gas expands when heated, so checking the tires "hot" results in both underinflation, and inconsistent inflation because you can never be sure exactly how hot the tire is.

I mean... you could fill them to <whatever> cold, then use an infrared thermometer to check pressure at various temperatures then graph it so if you air up on the road, you always know where you want to be... but that's a lot of work when it's easy enough to fill them cold.

Because PT Barnum was right.

There's no reason NOT to use it if it's free. To pay for it on any street vehicle is a waste of money. Air is already 78% nitrogen. Dumping the tire to "0" psi and refilling with pure nitrogen will still result in an oxygen content of around 7% at 40psi. You would have to fill and purge the tire 5-6 times to get the O2 content to under 3%.

Nitrogen is used in military and commercial aircraft for a number of reasons... the SR71 tires are pressurized to 600psi, but on any aircraft, a blown tire inside the wheelwell poses a serious risk of fire as both hydraulic lines, fuel lines, and electrical harnesses pass through the area. If the tire blows after retraction, the nitrogen content of the tire could be enough to prevent combustion in the confined area until the pilot can get the gear back down and make plans to return to the airport.