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Discussion Starter #1
I know we have several other posts in regards to pirelli tires but I wanted to bring some info to the front of the line. I have new Pirellis all around at the start of this year and have experienced some twitchyness in the front tire. I have been running what Suzuki reccommended for tire pressures which for 2 up are 33 front and 41 back(bridgestone tires). Well today I was checking tire pressures and noticed stamped on the side wall of the Pirelli that they reccommend running 38 psi in the front and 42 psi in the rear. Has anyone else noticed and tried these pressures? I adjusted mine to the sidewall reccommendation . I will see how they react and handle for a couple of days.

I'm interested to hearing other Pirelli owners thoughts.
 

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Just a thought... There is no way for Pirelli to know what bike a tire is going to end up on.
How much of a patch a tire leaves on the road is a function of the bike's total loaded weight AND the pressure inside.
The bike manufacturer has a good idea of how much their bike weighs and will weigh loaded, so their recommendation for pressure is based on that.

I think I'd email Pirelli, and ask them what they'd recommend if their tires were mounted on the Burgman with you on it. Otherwise I think I'd pick a pressure BETWEEN the bike amount and the tire amount. Since the Burgman's wheels are bigger than most scooters, Pirelli may normally sell those tires to larger heavier motorcycles. That higher pressure might be based on the assumption those tires are supporting more weight.

Dave B.
 

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4DThinker said:
Since the Burgman's wheels are bigger than most scooters, Pirelli may normally sell those tires to larger heavier motorcycles. That higher pressure might be based on the assumption those tires are supporting more weight.

Dave B.
However the weight of the 650 is about the same or is actually heaver than most sport bikes and crusers.
 

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What other bike/scooter/whatever would take these tyres - just as a matter of interest?
 

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Same thing I was thinking Norm. Except specifically - size - ...? What other bike use the same size combo?
 

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Norman,

I believe that the answer is "none". I think the Burgman 650 is the only machine that uses these tire sizes. So I'd be pretty certain that Pirelli does know what machine these tires are going to be used on.

But then, you probably already knew that... :wink:
 

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Allan,

I never noticed that sidewall pressure recommendation on the Pirelli tires. One psi pressure difference in the rear isn't such a big deal, but 5 psi in the front is significant. I washed the scoot today & plan to wax it tomorrow. While I'm at it, I'm going to have a good look at the front tire and see how it is wearing. I might also up the pressure for a week or so and see how it does. Thanks for bringing this up.
 

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4DThinker said:
Just a thought... There is no way for Pirelli to know what bike a tire is going to end up on.
How much of a patch a tire leaves on the road is a function of the bike's total loaded weight AND the pressure inside.
The bike manufacturer has a good idea of how much their bike weighs and will weigh loaded, so their recommendation for pressure is based on that.
Suzuki's recommendation is based on the standard tire they provide, which is the Bridgestone. Different tires will take different pressures, so you need to go by the tire manufacturer's guidelines if using a non-OEM tire.

Since tire pressure is affected by vehicle weight, using the same pressures on different weights of vehicles won't matter as the pressure will self-compensate for the weight difference (within reason). That's also why you need to check pressures with the tire mounted and the bike resting on it --don't have the bike on the center stand when checking the rear tire, for example.

HTH.
 

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Discussion Starter #10
Can somebody still sporting bridgestones do me a favour please and check the sidewall of there tires to see if there are any maximum pressures indicated there. Thanks in advance!
 

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Both front and rear are marked "MAX 41 psi" :wink: There are no Minimum markings.
 

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Snowride is right. My bridgestones agree. Max PSI is 41 for both. The maximum WEIGHT each can support is different though. 639lbs Rear and 494lbs Front. 1133 total pounds, which is a reasonable cushion over the 999lb gross vehicle weight maximum. Run the front tire at 33lbs, and it's max load would be around 398lbs, or 96lbs less.

Dave B.
 

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Allan, if I were you I would use the same logic that we all use when it comes to dealing with car tires, in the absense of other information, you go with the vehicle makers recommendations.
When I change from all season to snow tires, different makers, I use the same tire pressures. If I change from Michelin to Goodyear, same tire pressures.
You have had good feel and mileage using the max presures recommended so I wouldn't change your method if the ride still feels good. I hate to say this but it is up to your butt to let you know if it is happy. Sometimes it pays to listen to what your behind is feeling, wiggle wise!
 

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Allan,

I really haven't experienced that front tire "twitchyness" that you have talked about. I am thinking that your switch to 20 weight fork oil is a factor. The stiffer forks, combined with the Pirelli would be a different set of dynamics than what I have (stock fork oil, Pirelli tire, Ikon rear shocks).

Since changing fork oil is a lot harder than adjusting tire pressure ( :lol: ), you best bet is to play with the tire pressure until you find what works best for you. But I am thinking that your optimum tire pressure won't be the same as mine. We have each introduced more variables than just the tire change, due to our suspension modifications.
 

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Brian said:
That's also why you need to check pressures with the tire mounted and the bike resting on it --don't have the bike on the center stand when checking the rear tire, for example.HTH.snipped
That makes sense.
Never thought of it before.
So we should only check tire pressure while the burg is on the sidestand then to get an accurate reading.
Is that right?
 

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Uhm.... The pressure in a tire, no matter how much weight is on it, will be the same. What changes when you put more weight on a tire is the patch touching the pavement will increase. You can actually figure out the weight of any wheeled vehicle if you know the pressure in the tires and the square inches of pavement each tire covers.

I have a digital pressure guage that reads to the 1/10th. I put 40.2 lbs in my rear tire while it was on the center stand and off the floor. I pushed it off the center stand, tire on the garage floor, and it still had 40.2 lbs in it. I sat on the bike and had my wife check the guage.... 40.2 lbs.

The confusion is in believing a tire is like a balloon. With a balloon you can compress or inflate the total volume inside and effectively change the pressure of the air in there. But tires are constrained volumes. They don't stretch, and that's what allows you to decide how much air you'll put in them. The volume inside is essentially the same with 20lbs of air or 40lbs of air. The volume in the tire is the same no matter how much weight you put on it (within rated limits on the tire).

Now run the tire and warm it up, and as the air inside expands to fill the same space you'll get a pressure change. It's like putting more air in the tire, and that increases the pressure. As the tire cools so does the air in it. As the air cools it takes up less space and the pressure lowers.

Many tire shops are now advertising nitrogen gas as an alternative to air in your tires. It won't have the moisture content of air and so won't corrode your wheels. And I believe it is said to not change (so much) in volume as temperature changes.
 

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Discussion Starter #17
Well Pauljo you probably right about ending up at different pressures.

One small note of correction is that I changed my fork oil to 15 wt from the stock 10.

Well I've only been riding it 2 days with the adjusted ( more) air pressure and I must say that my butt much prefers the feel now. The scoot is much more planted now and the twitchyness is gone at the speeds I was travelling before (130km/hr)

The reason I started looking into it was on monday going into work I felt the front end slide for the briefest of milliseconds. However it was very unnerving. With the air pressure increased in the front it feels much better to me and I've yet to lose traction. I've actually ridden it harder now in the corners just to see if I get any feedback. It's planted and feels great. I may go out this weekend and play on a particular curvy road near me. I will start with the 38 psi in the front and take multiple passes reducing the pressure by 1/2 lb each trip. I will make sure the tires are already up to running temps before I try my experiment.
 

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4DThinker said:
Uhm.... The pressure in a tire, no matter how much weight is on it, will be the same. What changes when you put more weight on a tire is the patch touching the pavement will increase....

I have a digital pressure guage that reads to the 1/10th. I put 40.2 lbs in my rear tire while it was on the center stand and off the floor. I pushed it off the center stand, tire on the garage floor, and it still had 40.2 lbs in it. I sat on the bike and had my wife check the guage.... 40.2 lbs.
Try it at 36 pounds and see if you get the same result. Being near the maximum may have an affect.

I have been taught to always check tire pressure with the tires loaded. However that may have been based on old tubed tires, or only for aircraft tires, or something, so I'll accept that my infomration may be wrong.
 

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Discussion Starter #20
Thanks Dero!

Maybe the twitchyness I was feeling was tire flex. That would possibly account for the feel I had in the front end. Maybe thats why the higher pressure feels better to me, less flex. Like I said I will do some tests and reduce pressures untill the twitchyness comes back and then back up a step or two.
 
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