Tire Pressure Enquiry

[Bruno]

Hello,

 

I am in the process of doing the first service on my Guzzi. I changed the oil, which I should point out that I had to destroy the oil filter in order to get it off because it was so tight, and checked a few other things when I finally got to the tire pressure.

 

The front checked at 34 psi while the back tire pressure was about 35. I know from past experience that on a car, changing the tire pressure can greatly affect the handling characteristics. I assume that this is similar on a motorcycle.

 

The max pressure, as suggested on the tire for both front an back is 42 psi for the maximum load rating. The question is, does the maximum load rating equate to the best handling capability of the tire? If not, what would be the optimum tire pressure? Understandibly so, everyone has different riding abilities and depending on the requirements, i.e. whether driving in competition, touring, sport riding, etc. one wound expect different pressures.

 

Anybody have any thoughts on the subject? I spent some time searching for information on this site, but did not find any. I also checked the Guzziology book. There's is a lot of information relating to load rating, but I didn't find much in terms of recommended pressures. Maybe that's quite the right book for this type of information.

 

FYI, the tires are the stock Bridgestone 120/70ZR17 Front and 180/55ZR17 Rear

 

PS: Would anybody know the torque values for the oil pan bolts?

 

Thanks very much,

 

Bruno

[Guest vkerrigan]

Bruno.......This is liable to be as contentious as oil preferences, but I too have an 02 LeMans with the 020 Bridgestones. I run 34 front and 36 rear and have been satisfied with the mileage, wear pattern, etc. There are so many variables here that only you can know what feels good to you. It sounds to me like you're in the right range.....................vk

[Mike Stewart]

Bruno,

 

The tires show the max pressure allowed. This would be for a highly loaded bike. I would suggest using the spec. that is in the service manuel. It should also be printed somewhere on the bike. It may be covered up on the rear swing arm.

 

Mike

[docc]

I looked in the manual for the pan bolt torques but no-go. Are they 4mm ? There's a chart for torque by bolt size.

 

I'm running 34/38 on the Sport but it has a 160 rear with a small ( 4.5") rear rim.

[Bruno]

So I left the tire pressure as is. I have been riding this way since I got it. That was only 604 miles ago.

 

The bolts are 6 mm (I believe) hex recess heads. There's 14 of them. The size is OK I guess, but the fine threads (in aluminum) are going to get me eventually.

 

Bruno

[twhitaker]

The screws should be torqued to 8 to 12 lb/ft. Use a little bit of oil or, preferably, antisieze paste on the screws. As long as you do not overtorque them the tapped holes should last a long long time. My other bike, a 96 California, has the filter inside and the screws have survived 20 filter changes.

[antonio carroccio]

Can somebody explain me the equivalent of 10 PSI = ??? bar

[Guest bshpilot]

PRESSURE PSI -> BAR CONVERSION

[stormsedge]

I use the pressure from the manual as well, with Michelin Pilot Road tires. I have found that the bike handles okay with tire pressure over spec (up to 41 psi), but does not handle well if tire pressure is allowed to drop below the specs from the book. k

[Admin Jaap]

Can somebody explain me the equivalent of 10 PSI = ??? bar

Antonio, there is a link to an online converter top right of the forum.

[dlaing]

I use the pressure from the manual as well, with Michelin Pilot Road tires. I have found that the bike handles okay with tire pressure over spec (up to 41 psi), but does not handle well if tire pressure is allowed to drop below the specs from the book. k

I have found roughly the same that below spec is no good and a little above spec is fine, for handling and stability.

I once had a Pirelli factory rep explain to me how to get the pressure correct.

I don't remember exactly, but it went something like this:

Go for a 10 minute ride at say 30-50mph

measure the pressure

Go for a 10 minute ride at twice the speed say 60mph or as fast as you need to go

measure the pressure.

The idea is to set the pressure high enough so that it does not vary much after the two rides, but that the pressure is low enough that if you dropped the pressure a couple pounds the difference in pressure between rides would be significant.

That was what I got out of his explanation, he might say I got it all wrong, and what he said was "significant" could have been five or ten or fifteen pounds. Sorry I can't remember ; (

It would have been useful to know.

Basically you do not want the tire to flex so much at high speeds that it causes the tire to heat up too much.

A good experiment would be to try the test at Guzzi spec pressure and then try it at maximum pressure. Then try to get the pressure as low as possible while maintaining a pressure difference between speed tests that is nearly equal to that of maximum pressure results.

Of course few will want to go through all that trouble... I have not.

And I'll bet older tires would need more pressure following that test because the thinner carcass would flex more.