Coincidence?

[Sandy]

I haven't used the percent method much in the last number of years but it does work. The percent increase is basically an old school method of making sure the tire is running at a good temperature. Too small of a differential percentage means your tires has too much air and too high of percentage generally means the tire is running too hot .....generally from not enough air but other factors such as overloading or wrong tire could also come into play. Someone mentioned 20% for a rear ...that would mean your tire is running way too hot. Depends on riding style as well. I used to use about 8 - 10% on the street and 10 - 12% on the track and only measure after you've gotten the tires nice and hot ...that's the fun part. LOL.

[fbody_mike]

Good results from my first sample. Checked the pressure the morning on the 2004 Bandit and it was at the 36 psi that Suzuki recommends. Had a nice spirited 40 minute ride, checked the pressure as soon as I parked it and it was just a hair under 40 psi for both front and rear. That is a delta of right around 10%. Pretty neat.

[Gorminrider]

Whatever you want to look at to account for older tires rated to carry their maximum at 32 or 36 psi and newer tires at 46 psi

I don't want to make a big deal of this But I think it's one of those ethings that gets overblown...and is tossed in. It so happens I have a 1985 Avon book.That's 34 years ago

A few examples:
the tubeless SUPER VENOM has max (cold ) pressure of42#.
the tubed SUPREME has a max (cold) pressure of between 36-40#

A much newer catalogue of Bridgestone says that the BT45 has max pressures of 41-45#
and speed ratings H or V depending on the model

Granted that high end tires nowadays have increased speed ratios, (W and above) most of us are still using and buying H and V today. (up to 130mph) though Avon claimed 137mph for the V rated Super Venom in 1985....


If I had a 1985 tire or a 2019 tire, none of this is going to cause me to change my inflation pressure. It's irrelevant for a 1980 motorcycle riding on the street

PS the nearest many tires get to the Max(cold) pressure is when they are mounted. Indeed , instructions or notes I have from manufacturers that mention mounting to tubeless rims do seem to agree with this maximum.

[Rob S.]

Just looked up in the HD owner's manual and it says 36 front, 42 rear cold. So that's where I got those numbers from.

When I ride tomorrow, I'll look and see what numbers are on the side of the "Michelin Scorchers."

[Cipher]

Like mentioned earlier, Pirelli recommends 32/36 psi. Why question further? The tires should not be set at the max allowable pressure unless there is specific reason to, such as carrying a heavy load.

Or for gas mileage. Fear and loathing in Las Vegas what did they have the caddy tires at? 75 psi?

[Gorminrider]

Just looked up in the HD owner's manual and it says 36 front, 42 rear cold. So that's where I got those numbers from.

When I ride tomorrow, I'll look and see what numbers are on the side of the "Michelin Scorchers."

as to "suitability", Tire manufacturers often mention tires for Harley Davidsons specifically. Or, best, consult Harley Davidson. You should not run out and put on just anything that "fits" and pump it up to suit Harley's owner's manual. You should not run at or very near the tire's marked maximum cold pressure.

[Rob S.]

as to "suitability", Tire manufacturers often mention tires for Harley Davidsons specifically. Or, best, consult Harley Davidson. You should not run out and put on just anything that "fits" and pump it up to suit Harley's owner's manual. You should not run at or very near the tire's marked maximum cold pressure.

They are the original tires that came with the bike. That make any difference? (They have 3k miles on them).

[Who Dat?]

They are the original tires that came with the bike. That make any difference? (They have 3k miles on them).
2016 XL883L (Almost 42 HP!)

Are you at all worried about the high mileage ruining your resale value?

[Datsa Noydb]

I was kinda noticing that, too. But, ... at 100 mph every time out, it wouldn't take very long.

[Rob S.]

I have no intention of ever selling either of my bikes. Sure, more would be better, but two is still a dream come true.

[Agemax]

I was kinda noticing that, too. But, ... at 100 mph every time out, it wouldn't take very long.

100MPH........... on a Harley???????

[Gorminrider]

They are the original tires that came with the bike. That make any difference? (They have 3k miles on them).

just sayin' is all. Your Michelins that are on are "Harley badged" so how can they be wrong?( I guess it's a pretty heavy bike...)
The coincidence I'd guess is that the Harley and the Suzuki weigh the same , having same tire pressure to hold them up is not so suprising.
It'd get more complicated as a comparison where the two bikes had different footprints entirely...the Harley wanting a big wide contact patch at the rear (wider,+ lower profile maybe) versus...something else. Which gets me back to the Harley-Intended refrain... I don't have a Harley but I think I'd be leery of putting Sport Demons on. Don't know about Michelin "Scorchers" either.

I hope your tires aren't worn out with 3k miles on em. Hot streets where you are or it's your own fault!

[Rob S.]

The Sport Demons are on the Suzuki. Problem with that?

Michelins came with the Sportster.

The bikes weigh just about the same (565 lbs).

[fbody_mike]

Just to follow up on the 10% rule. My 82 XJ650LJ (turbo), had specs for 28 psi front and 28 rear from the factory. Now add a passenger or high speed riding, it said to go to 32 psi on the rear only.
With 28 in the front, I got a 10% delta after a nice spirited ride.
The rear with 32 psi, I got a 17% delta. Which should mean it was too hot and needs more air pressure. So I went up in 2 psi increments until I found a 10% delta which turns out to be 38 psi.

It is interesting because a while back Avon had a lookup program on their website that would suggest which of their tires to use and how much psi to use with it. I think it was on their UK site, but for this bike, they recommended 33 psi front and 40 psi rear. I run Michelin Pilots on it now, but the more I compare notes and measurements the more I like this 10% rule for inflation.

Now for the 550 with its Sport Demons, once I get it back together.

[Sandy]

Just to follow up on the 10% rule. My 82 XJ650LJ (turbo), had specs for 28 psi front and 28 rear from the factory. Now add a passenger or high speed riding, it said to go to 32 psi on the rear only.
With 28 in the front, I got a 10% delta after a nice spirited ride.
The rear with 32 psi, I got a 17% delta. Which should mean it was too hot and needs more air pressure. So I went up in 2 psi increments until I found a 10% delta which turns out to be 38 psi.

It is interesting because a while back Avon had a lookup program on their website that would suggest which of their tires to use and how much psi to use with it. I think it was on their UK site, but for this bike, they recommended 33 psi front and 40 psi rear. I run Michelin Pilots on it now, but the more I compare notes and measurements the more I like this 10% rule for inflation.

Now for the 550 with its Sport Demons, once I get it back together.

Perfect understanding and application for this method. Funny that years ago I did the same thing with my GS1000 which is about the same weight and probably power as well and runs the same tires sizes. With the Dunlop GT501s that I used for years I settled on 32/38. I switched to Battleaxes last year so just for giggles I should rerun the tests to see if there is a different result.