Author Topic: Tyre problems 80+  (Read 4489 times)

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Offline KiwiJohn

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Tyre problems 80+
« on: 24 Aug 2008 at 21:04 »
Hi, this is probably not a Duggie specific problem and quite likely points more to my general inexperience with motor cycles!

I have a problem that just about every time I take my 80+ out one or other of the tyres will  suffer a flattie due to the valve stem coming away from the tube.  Needless to say this rather inhibits my enthusiasm for going a bit of a spin!

Initially I cursed the Chinese tube makers but that might have been unfair and something else if causing the damage.  This I can only imagine is the tyre moving on the rim?

There were big clunky clamp things which I think go inside the rims, these are not fitted, should they be?  Should I use some sort of adhesive on the rims?  Is it a case of tyres too old?

Thanks for any comments.


Offline Doug

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Re: Tyre problems 80+
« Reply #1 on: 24 Aug 2008 at 22:06 »
John,

If you had alloy rims, they may be a little to 'slippery', allowing the tire to slip on the rim. However I have Ackront alloy rims fitted to my Mark 3 Sports, and only pulled a stem out once on acceleration (such acceleration as it is...) when I allowed the rear tire pressure to fall very low.

Some aluminum rims use to have the side of the well knurled, and some racing rims had four holes through the side of the rim to run a sheet metal screw through and into the bead of the tire.

You could also fit a security bolt, as you described. They are a bit of a pain when dealing with tire changes though, but they do a good job clamping the tire to the rim, especially when running low pressures. Hence there use on trials and off-road bikes.

I run 28-30psi in the rear wheel of the Mark, to try and give a little more cushion to my lower back. Not sure how low it got before it slipped on the rim, as the next time I checked it it was zero!

Are you using soap or powder on the rim to help ease the tire on and off,  or something that might leave a residual lubricant behind?

-Doug

Offline KiwiJohn

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Re: Tyre problems 80+
« Reply #2 on: 24 Aug 2008 at 23:35 »
Doug,  I dont change the tyre myself but I did wonder at the machine at the local tyre shop which does seem to put a lot of pressure on stretching the beads!  The tyres have been on and off so many times they might well be contaminated with old lubircants so that is an angle for me to attack.

New tires might be in order when I think of how old these are! :mrgreen:

Offline eddie

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Re: Tyre problems 80+
« Reply #3 on: 25 Aug 2008 at 07:35 »
John,
          Originally the rear tyre would have been a 3.25 x 19 on a WM2 rim (1.85" wide) with 22 lbs / sq in pressure - these figures being for standard road use. If the tyre section or rim width has been altered, it may effect the seating of the tyre bead in the rim and be the start of your problems. I have used the 'cheapie' Oriental tubes without any problems other than slight porosity giving rise to gradual pressure loss - about a pound every 2 days. (Always check tyre pressures prior to riding). With the original Dunlop rims and tyres, some lubrication and about 40 psi is usually needed to get the tyres to seat correctly on the rims - if yours are going into place much easier than that, perhaps you should invest in new rubber, as they have probably been strained or are getting somewhat geriatric. If rigor mortis is setting in, I would have expected the tyre bay mechanic to have commented!
        Security bolts were listed for the Plus series, but were not really needed for general road use. A little dodge we used to use on our old scrambles bikes, was to fit the tyre and before inflation, turn it in the direction that it would normally rotate - this makes the valve lean back - if the locking ring is then left loose, you can periodically check the valve angle to see if creep is occurring (before having to spend out on another tube!). The front tyre only suffers braking forces, so the valve should be leant the other way!
                                     Regards,
                                                  Eddie.

 

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