Dunlop Q2's loosing psi on freeways

[arebman]

Hey there,

I was on the freeway the other day well into triple digits, and my new Dunlop Sportmax Q2's (32/32) lost about 1/2 the air pressure over the sprint. I am curious if there are "tricks" or a right way to not loose the tire pressure?

The tires handle everything else just fine.

I am curious if there is anything I should (besides the obvious NOT doing that.)

Thanks

 

[ebster1085]

You lost half the air pressure or half a psi??

 

[arebman]

Oops, I was at 20psi when I pulled off, i had checked the pressure before heading out (32/32) and they were fine for a whole week before that (staying under 90 on freeway no more than 5 min).

 

[Darth Fazer]

Hey there,

I was on the freeway the other day well into triple digits, and my new Dunlop Sportmax Q2's (32/32) lost about 1/2 the air pressure over the sprint. I am curious if there are "tricks" or a right way to not loose the tire pressure?

The tires handle everything else just fine.

I am curious if there is anything I should (besides the obvious NOT doing that.)

Thanks

Do you have good-sealing tire valve stem caps installed? I have heard of centrifugal force at high speeds opening the valve cores & bleeding air out. Other than keeping dirt out, valve caps also help prevent air loss at higher speeds.

 

[arebman]

They are clean, but as for good sealing, that I do not know. My next test is going be a longer ride at about 80-90 mph and see what happens.

There were no holes or anything, and I re-inflated them and everything worked fine.

I will check on the caps/valves tonight. I do know the caps have a little metal piece in them?

 

[Darth Fazer]

They are clean, but as for good sealing, that I do not know. My next test is going be a longer ride at about 80-90 mph and see what happens.

There were no holes or anything, and I re-inflated them and everything worked fine.

I will check on the caps/valves tonight. I do know the caps have a little metal piece in them?

You want to make sure they have a little rubber o-ring inside them to seal when you tighten them down. I prefer a metal cap. I'd stay away from those caps that let you know when the pressure goes down, because they work by actually depressing the valve stem all the time. I don't know about any little metal pieces in them? You could have a fauty valve or core. The only other thing I can think of that would affect the pressure at high speeds is if you took off fast and the tire rotated on the wheel (in other words, the wheel spun faster than the tire). That usually only happens if the tire's been freshly mounted & still has lube on the beads.

 

[ChevyFazer]

If the tire has been on a while and this is the 1st time this has ever happened it sounds like you might have some sort of puncture in the tire.

 

[arebman]

View attachment 42287

Here is a picture of the caps I have, I can blow through one side and feel a tiny amount of air out the other... stem problem?

 

[ChevyFazer]

Put soapy water on the valve stem itself, if it bubbles it's leaking, the cap is there for added protection but the stem shouldn't leak period

 

[arebman]

Just did the soap trick, there is no leak, even when someone of my equal (give or take) weight is sitting on it.

This leads me (thanks by the way for the minor trouble shooting) to aim towards the strait forward question: Has anyone had a pair and opened them up to 100-120 mph for about 5-8 miles? Or am I pushing them too hard?

 

[ChevyFazer]

Q2's are a top quality tire and shouldn't loose pressure for any reason other than a puncture, other than pressure temp changes which is normal for any tire. have you checked to makes sure there isn't a puncture?

 

[red_rock_beetle]

let me ask you something, do you have an angled valve stem? because if so, at higher speeds this type would be affected more by centrifugal force because of leverage, i would make sure ,if you do, that they are tight because if they are loose they may seal fine normally but at speeds be pushed enough to create a leak

 

[ChevyFazer]

let me ask you something, do you have an angled valve stem? because if so, at higher speeds this type would be affected more by centrifugal force because of leverage, i would make sure ,if you do, that they are tight because if they are loose they may seal fine normally but at speeds be pushed enough to create a leak

That's true, didnt think about something like that. If he does have those he could put the soapy water on it then push it down and see what happens. If he can't make it leak with his finger then I wouldn't think it would leak at speed.

 

[Darth Fazer]

What I meant earlier is not that the stems are faulty & leaking, but that the centrifugal force can actually open the valve core (the little button in the stem you push open with the air chuck to add air to it) at high speeds, especially if the core's spring is weak. The valve cap can minimize air loss under these circumstances. If this is the case, you would not find a leak while parked, only while at high speeds. I think you should replace the tire valve's core as a safety precaution (they just screw out with a special tool). Any tire dealer (including car tire dealers) will probably give you one & put it in for you for free or next to free. If not, any auto parts store or even Wal-Mart will sell you a kit that has 4 stem cores, a core tool, 4 valve caps & probably an air gauge for less than $5. You may have another problem, but as cheap as you can replace the core, I'd just do it to be on the safe side. Obviously, I'd be close to an air supply when I replaced them.

 

[arebman]

Ok, sorry for the delayed reply, have been busy with school,

The latest update is this:

Took the bike out on the freeway some more, and was hitting triple digits multiple times for longer periods,

Before all of this, I replaced the caps on the tire stems with the ones like on a car wheel. Have not had any air issues yet.

My next part I am going to add on, is that I am going to look into replacing those tire stem valves as an added precaution. And yes, these really are good tires. Great on the turns and such.

Thanks for all the help, and I will keep updating on what I do / experience.
Also any other tricks I will also make sure to try

 

[arebman]

That's true, didnt think about something like that. If he does have those he could put the soapy water on it then push it down and see what happens. If he can't make it leak with his finger then I wouldn't think it would leak at speed.

What I meant earlier is not that the stems are faulty & leaking, but that the centrifugal force can actually open the valve core (the little button in the stem you push open with the air chuck to add air to it) at high speeds, especially if the core's spring is weak. The valve cap can minimize air loss under these circumstances. If this is the case, you would not find a leak while parked, only while at high speeds. I think you should replace the tire valve's core as a safety precaution (they just screw out with a special tool). Any tire dealer (including car tire dealers) will probably give you one & put it in for you for free or next to free. If not, any auto parts store or even Wal-Mart will sell you a kit that has 4 stem cores, a core tool, 4 valve caps & probably an air gauge for less than $5. You may have another problem, but as cheap as you can replace the core, I'd just do it to be on the safe side. Obviously, I'd be close to an air supply when I replaced them.

I am going to try replacing the core valves next. I have not been back up to the same speed and length as before (120-130 ish) but I have been running around at about 100 for a few miles, and there has been no problems.

 

[ctbandit]

Just did the soap trick, there is no leak, even when someone of my equal (give or take) weight is sitting on it.

This leads me (thanks by the way for the minor trouble shooting) to aim towards the strait forward question: Has anyone had a pair and opened them up to 100-120 mph for about 5-8 miles? Or am I pushing them too hard?

:shakehead:

 

[arebman]

:shakehead:

Yeah, I know... :spank:

 

[arebman]

What I meant earlier is not that the stems are faulty & leaking, but that the centrifugal force can actually open the valve core (the little button in the stem you push open with the air chuck to add air to it) at high speeds, especially if the core's spring is weak. The valve cap can minimize air loss under these circumstances. If this is the case, you would not find a leak while parked, only while at high speeds. I think you should replace the tire valve's core as a safety precaution (they just screw out with a special tool). Any tire dealer (including car tire dealers) will probably give you one & put it in for you for free or next to free. If not, any auto parts store or even Wal-Mart will sell you a kit that has 4 stem cores, a core tool, 4 valve caps & probably an air gauge for less than $5. You may have another problem, but as cheap as you can replace the core, I'd just do it to be on the safe side. Obviously, I'd be close to an air supply when I replaced them.

Took the bike in, and the place i got the tires from threw new cores in for free, they are also baffled and excited to hear my results.

 

[kennedyted]

ok so im trying to replace the valve stem in my rear tire, places here in erie want 40 bucs to put a valve stem inn, and most places are telling me they cant do a motorcycle tire, i dont need it mounted balanced or **** even air in it, i just want a valve stem replaced wtf