Touring and twisties and heat -- what's the tire pressure compromise???

[MacDoc]

So hard to get to the Burgman 650 tire valves to get an accurate read I broke down and bought the above which works the charm.

That said . We set it up 40 and 40 cold ( one of the most experienced riders on the Burgman forum whom all rely on for advice recommended this ) which I found too stiff on the front end so dropped it to 39.

That seemed fine most of the day of a 200 mile ride today through the twisties. As the tires heated it got to 41 and 43 which was acceptable.

But later in the day as the temp rose it got to 43 and 47!! and I really found the front end jarring at that kind of pressure on downhill twisties.

Now I'm torn as I like the lighter feel the higher pressure in the warmed up tires gives but was surprised at the range of change.

Anyone else using a real time gauge have some insight.

Going for a longish ride in PA twisties and want to settle on a cold tire pressure that gives me reasonable stick and ride comfort even when it gets hot.
Any thoughts. I'm thinking of seeing how it does over time and if there is any pressure loss but damn that was jarring and a bit uncertain with pressures up that high ( Metzlers on ).

http://www.burgmanusa.com/forums/viewtopic.php?f=4&t=31795&start=0

This was the related thread and in light of how high the pressure goes up on a hot day/ride - maybe Suzuki's 33/36 has some value as from the looks of it that could end as high as 38/41 when fully warmed and I certainly felt the bike to be more skittish when the pressure was up in the 40s hot.
I'm 250 lb with 20 lb of luggage carried regularly.

The higher pressure of course improves mileage and perhaps tire wear at the expense of ride comfort and perhaps cornering traction.
The Burgman is not stellar ( understatement ) in the suspension end so is sensitive to tire pressure.

Thoughts? I know it varies from bike to bike but I must admit I was surprised at the range of change and correct tire pressure is a common concern.

 

[silverbullet132]

Have had no issues keeping the burg at 40/42 cold. Runs great in twistiest even when hot. Rear suspension set at #3.

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[MacDoc]

I'm wondering what ambient temps were when you were riding?
As I mentioned I was fine until it got over 30 in the afternoon and the pressure spiked in the tires.

 

[Brian P]

I am not familiar with the tires on those particular bikes, but on other bikes, it's not uncommon to have to lower the pressure in order to get adequate tire temperature when doing backroads but raise it in order to avoid overheating the tires on motorways.

 

[MacDoc]

I am not familiar with the tires on those particular bikes, but on other bikes, it's not uncommon to have to lower the pressure in order to get adequate tire temperature when doing backroads but raise it in order to avoid overheating the tires on motorways.

Think you got that reversed but point is the same.....

Tires are the same just a tad smaller 15s - I need a compromise range as getting at the valves is so nasty it's not something you can do reliably on the road.
Clearance to the valve is very small due to dual discs and smaller diameter. You can see the issue. Also how many actually change their tire pressure depending on conditions ( aside from off road where it's almost mandatory ).

Very different access than the 21" on the KLR

versus Burgman's 15" and 14"

Front Tire (Full Spec) 120/70 R15 M/C 56H
Rear Tire (Full Spec) 160/60 R14 M/C 65H

I was just surprised at the high range of pressures from cold to hot day twisties. Looking to see where others run theirs cold.

 

[Brian P]

I don't have it reversed. Normal sport tires need to be run in the 30 psi range give or take to get enough tire temperature in them when doing twisty roads, but raised up to 36 or even 40 psi to prevent them from melting at higher speeds.

 

[silverbullet132]

I'm wondering what ambient temps were when you were riding?
As I mentioned I was fine until it got over 30 in the afternoon and the pressure spiked in the tires.

Seemed to have no issues even riding on those 40c days. What did you set your rear shock at?

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[MacDoc]

The rear is not an issue ( 3 ) but could feel it was a tad skittish - the front was simply too hard for my comfort level once it got hot. It was only in the mid 30s tho.
When you were running in the 40c days did you actually check your tire pressure when hot??

•••
Brian P
Not sure what you mean by "normal sports tires" - these are Metzler FeelFree for high speed touring/handling so I would think they are "sports tires" - the Burgman weighs in around 600 lb.

* Optimized wet performance, thanks to a high contact area and a dedicated contour to provide high-speed stability, outstanding cornering behaviour and excellent handling
* Excellent riding comfort, long mileage, even wear, thanks to the compound and tread pattern design based on the same prizing motorcycle sport-touring tyres concepts

are you saying they run cooler at the higher pressure???

I can understand lowering for the twisties for grip but I'm still not clear about running higher pressure for highway as I would think long runs at high speeds 130+ would increase the pressure most.

 

[Brian P]

Higher pressure for high speed operation allows the carcass to flex less, so that less heat is generated in the tire.

Yes, the actual operating pressure in the tire will be up there and yes, it will be noticeable in ride quality. But the alternative is excessive tire wear down the middle.

 

[MacDoc]

Yeah that's what I'm trying to find is a decent compromise - just went from cold to high speed for 30 minutes..

39 and 41 goes cold to 43 and 47 at 120 kph steady at 30 degrees ambient.

Gauge sows tires at 93 degrees F and 117 F front and rear.

I dropped the front down to 39 cold and that seems better - not so jumpy - might try another lb down
Gonna run in the minor twisties on the way to the Forks - see how it feels today.

 

[Flywheel]

Not to sound snippy, but your money would be better spent on upgraded springs and emulators. New rear shocks are nice, but a bit expensive and not totally necessary; fixing the front yields better results. I fiddled around with pressures, but ended up leaving them stock (33 front, 41 rear). I initially thought the stock suspension was okay, but the more you push, the more it shudders. A set of springs from sonic and racetech knockoffs would only run about $150.

Now that I have new Michelins on and not 2004 vintage, squared-off and lopsided tires, I expect even better results. How do you get lopsided tires anyway?

 

[MacDoc]

Not interested in either - have not found fault with the handling except about 150 on rough sweepers.

I don't know where you are getting the idea I am spending money. I want to know what my tire pressure is as that's HOW you end up with lopsided, squared off tires by not paying attention to it.

 

[Flywheel]

More of a technical question--they were definitely squared off when I bought the scoot. The tire seemed odd, but I didn't really notice the lopsided-ness until I took the wheel off recently. Since I check pressure on a regular basis and don't ride in counterclockwise circles, it's a bit of a puzzle.

"So hard to get to the Burgman 650 tire valves to get an accurate read I broke down and bought the above which works the charm."

^That's where I got the idea you were spending money. Did you mean it was much less expensive and better way to deal with the suspension?

 

[MacDoc]

No - it's a good investment to know the state of the my tires as getting an accurate consistent reading with that valve stem positioning is a total pain and now I can check every ride and during the ride - In my view that's a good thing.
The suspension is not an issue - I do have a later model 650 but I was content with it on the 2005. I was never content with the tire pressure difficulty. Now I'm fine and want to fine tune between acceptable sticky in twists and decent mileage and wear.
The real time gauge will let me do that reliably.