Tested my tires at the 10% rule

[willowstreetguzziguy]

Have a Michelin Pilot 4 on the front and a new Pilot 5 on the rear. Inflated BOTH to 39 lbs before going on a 200 mile ride Saturday. Upon returning I found the

Front hot up 3 lbs to 42 lbs...  up from 39   Should I raise it to 40-41 lbs cold?

Rear hot up 5 lbs to 44 lbs... more than 10%   Should I lower it to ~37 lbs cold?

Does that sound right?

 

[oldbike54]

 The front is good .

 The rear needs a bit more cold pressure . Low pressure creates heat because the tire is squirming about creating friction which causes heat .

 Dusty

[willowstreetguzziguy]

The front is good .

 The rear needs a bit more cold pressure . Low pressure creates heat because the tire is squirming about creating friction which causes heat .

 Dusty

Thanks, and here I thought higher pressure might cause heat but I guess not.

[kingoffleece]

I'm with Dusty here.  But, (there's always a but, eh?) as you're in the ballpark you can try and extra pound in the front.  It can make a difference for some set-ups and some are more sensitive about it.  The 10% rule gets you in the ballpark with a good seat-you may want to move around a bit for a better view but you are certainly ok where you are after a small tweak in the front.

[LowRyter]

Have a Michelin Pilot 4 on the front and a new Pilot 5 on the rear. Inflated BOTH to 39 lbs before going on a 200 mile ride Saturday. Upon returning I found the

Front hot up 3 lbs to 42 lbs...  up from 39   Should I raise it to 40-41 lbs cold?

Rear hot up 5 lbs to 44 lbs... more than 10%   Should I lower it to ~37 lbs cold?

Does that sound right?

39lb on a 1200 Sport?  I am not sure what the book says but that seems a little on the high side.  Typically 35 front and 38 rear (cold) for most sport radials.  I have no idea what your books says.

[Darren Williams]

39lb on a 1200 Sport?  I am not sure what the book says but that seems a little on the high side.  Typically 35 front and 38 rear (cold) for most sport radials.  I have no idea what your books says.

The Sport is a bit of a heavy bike. I ran my 1200 Sport at 36F/40R with Angle ST tires. They would stay pretty close to the 10% rise rate and the feel and tire life was pretty good.

And Dusty is right on the mark about lower pressure causes more friction heat build up.

[oldbike54]

Thanks, and here I thought higher pressure might cause heat but I guess not.

 That is a common misconrception . Think about this for a moment , higher air pressure simply means you have added a greater volume of air into the tire decreasing rolling resistance and side wall flex , thus decreasing friction and heat which causes a rise in pressure . If you are only riding short distances or on a race track heat is an ally , but it is the enemy of any type of sustained street riding .

 Dusty

[yogidozer]

Can't go by "the book" Each tire brand needs to be checked with the 10%.
Different structures, materials, and different brands are not exactly the same sizes, despite what the sidewall says.
Riding style, weight, also factor in.

[oldbike54]

Can't go by "the book" Each tire brand needs to be checked with the 10%.
Different structures, materials, and different brands are not exactly the same sizes, despite what the sidewall says.
Riding style, weight, also factor in.

 That , and as Darren mentioned , loading plays a factor . More weight = more rolling resistance = more friction= more heat .

 Dusty

[Moto]

Can't go by "the book" Each tire brand needs to be checked with the 10%.
Different structures, materials, and different brands are not exactly the same sizes, despite what the sidewall says.
Riding style, weight, also factor in.

The sidewall pressure is not a recommendation.

[yogidozer]

The sidewall pressure is not a recommendation.

I'm talking about the owner's manual. I don't consider a tire sidewall a book 

[Gliderjohn]

I need to try this out. My Norge came with Perilli Angel GTs. The Owner's manual calls for 41 rear and 39 front regardless of load. Now since that model tire is what the bike came from the factory with I am to suppose the recommended pressure is for that tire on that bike. Will see if the 10% works with it.
GliderJohn

[wirespokes]

The ten percent is just an average. Most tire gauges don't read real fine differences in pressure. The way I originally heard it was 8% rise in front, 12% rear.

[Darren Williams]

I need to try this out. My Norge came with Perilli Angel GTs. The Owner's manual calls for 41 rear and 39 front regardless of load. Now since that model tire is what the bike came from the factory with I am to suppose the recommended pressure is for that tire on that bike. Will see if the 10% works with it.
GliderJohn

Lucky you. All 3 of my CARC new purchases came with Metzlers (which I don't really like much). The Norge may be carrying a bit more down force on the front at speed than the sport did, due to the fairing?  If I ran 39 in the front on the Sport it would only have risen a couple psi. Sport touring tires, like the Angels or Road 4/5's will have a stiffer side wall that will help control deflection, and thus heat. That's why an accurate gage and testing can help with feel and longevity.

If I run the back pressure too high they will square off in no time at all, with my riding in the flat part of Oklahoma so much.