betarick Posted March 15, 2015 Report Share Posted March 15, 2015 Anyone 1 had problems with evo rear tyre going flat only when riding ? New Dunlop and valve fitted any rim issues. Quote Link to comment Share on other sites More sharing options...
steve_earle Posted March 15, 2015 Report Share Posted March 15, 2015 It might be due to the harder compund of the Dunlop. It might be leaking around the rim when let down to trials pressure. It might be worth breaking the bead and using what the tyre fitters call beadsealer, glue like stuff that you brush on the rim. Failing that, a can of tyreweld always does the job. What made you choose a Dunlop? Quote Link to comment Share on other sites More sharing options...
p@ul250 Posted March 15, 2015 Report Share Posted March 15, 2015 (edited) I've been running with Dunlops on my outfit for the last two years with no problems. You have either damaged the valve stem or the tyre when fitting them. I choose the Dunlop because it stays on the bead when subjected to the high side loads (rolling) we get. Edited March 15, 2015 by p@ul250 Quote Link to comment Share on other sites More sharing options...
goudrons Posted March 15, 2015 Report Share Posted March 15, 2015 I've not heard of this with Dunlops, but tubeless IRC's don't fit the new style Morad rims properly (with the spokes on a flange rather than through the rim). They can deflate when they take a hit like a rock or log. I seem to think the beading is a problem, not quite tight enough fit because the IRC's inner diameter is ever so slightly larger. I've a new IRC sitting uselessly as I went back to a Michelin, which cured the problem. I believe if you fit a Michelin, either standard or lite, if should be ok. Quote Link to comment Share on other sites More sharing options...
betarick Posted March 15, 2015 Author Report Share Posted March 15, 2015 No damage to bead on tyre and I have always used Dunlops with no problems tyre seems to last half trial distance then is flat! Had wheel in a bath and no leaks 2nd tyre now that as leaked even with a new complete valve! Quote Link to comment Share on other sites More sharing options...
fastbelly Posted March 15, 2015 Report Share Posted March 15, 2015 You may have a damaged/cut tyre which only lets air out once a revolution when it flexes at the bottom. Just putting an idea out there. I had a rear tyre on a CB500 that went down only if I parked it with the wheel in the wrong place. Quote Link to comment Share on other sites More sharing options...
goudrons Posted March 16, 2015 Report Share Posted March 16, 2015 Hers's a link to the IRC problem http://www.trialscentral.com/forums/topic/37953-irc-rear-tyre-problem/ I've been told that some suppliers aren't stocking IRC's any more due to the amount of bikes with DID and DID "style" Morad rims as they know about this issue. (with the spokes through a flange rather than the rim) They are getting too many back with this impact-deflation problem. I suspect you are suffering the same issue with a Dunlop, as you have tried two different Dunlops, replaced the valve and it does not leak when not ridden, but it's loosing air when impacted on a step/rock/log etc. It's not the tyre, but the new rims together with the tyre. Tyres aren't holding a seal once the tyre takes an impact, one bump and the bead is being broken. When I replaced my new IRC with a new Michelin Lite because of the above issue, it became apparent the Michelin was a lot tighter on the rim as it was a real bugger to fit, where the IRC popped on fairly easily. The tyres walls of the Michelin weren't opened out like the IRC, so tightly together I had to force both sides beadings on together with lashings of tyre soap in one go (and bruised knucles) The IRC popped on one side at a time without much soap. See if you can borrow someones old/spare Michelin, I'll bet it cures your problem. Quote Link to comment Share on other sites More sharing options...
betarick Posted March 16, 2015 Author Report Share Posted March 16, 2015 Bike came new with a Michelin no problems with tyre. 2nd tyre Dunlop was ok and was swapped round to wear both edges then finished a trial with it flat so was replaced as I thought it was punctured.3rd tyre new Dunlop went flat doing bemrose and came off rim and damaged valve inside rim and had to ride it off moors.just replaced with a new Dunlop d803gp and new valve checked rim no damage or mark's.rode Cleveland national and managed to do 20 sections then noticed it was flat and it pumped up ok rode rest of trial and was flat at last section! Blew it up to 10psi last night and just checked now and it's still at 10psi! Quote Link to comment Share on other sites More sharing options...
dadof2 Posted March 16, 2015 Report Share Posted March 16, 2015 The Dunlops are generally a tighter fit on the rim than a Mitchelin, that is why they don't come off so easy when flat or subject to side load. This tightness can stop them installing properly on the rim, meaning they leak intermittently when subject to flexing. These problems are more likely if tyre installed in cold weather. Keep tyre and rim in warm room for a few hours with tyre on rim but not seated nor inflated. Thoroughly coat rim and beads seating area with contact adhesive and immediately inflate to 45 PSI. Leave in warmth overnight. Quote Link to comment Share on other sites More sharing options...
betarick Posted March 16, 2015 Author Report Share Posted March 16, 2015 Never had any problems before with my 2011 evo or rev3 fit god knows how many rear tyres and always used Dunlops after Michelin on new bikes wear out as they stay on rim when punctured. Temp of rim or tyre as never been a problem. And living in Silsden I have a constant supply of Dunlops!! Quote Link to comment Share on other sites More sharing options...
dadof2 Posted March 16, 2015 Report Share Posted March 16, 2015 Obviously I don't know why you have suddenly had a problem. What I do know is that rim sizes and bead seating areas vary quite a bit when you would expect them to be constant. Also tyres vary both regarding bead diameter and the thickness of rubber over the cords in the bead area. Warming the tyre softens and expands it and the impact adhesive lubricates it so it slides into place on the rim. Without lubricant it can bind, stopping slightly short of fully seated. http://www.yokohamatire.com/tires_101/tire_care_and_safety/match_mounting/ See above link. Some manufactures use several more colours to match tyres to reduce the effects of manufacturing variations. I once had problems with a front tyre (tube type) that would seat and run true at 30 PSI but would not stay seated when pressure was reduced to trialling pressure. Method I suggest cured it. Quote Link to comment Share on other sites More sharing options...
housty90 Posted May 20, 2015 Report Share Posted May 20, 2015 I have had 3 or 4 new Dunlop GP803's over the course of the ssdt and the weeks since and ALL have been going flat. Last weekend I was out and had to take a pump and gauge with me as my rear tyre was dropping from 4.2psi to less than 2psi in one hour. Doing my nut in. Tried everything cleaned the bead swapped tyres pressurised it right up to try and seat it but nothing working, still leaking from the bead. I know someone has said about putting sealant on the bead but that's not a solution it's simply a bodge job. You wouldn't accept it with your brand new car tyre so why accept it with a trials tyre. Maybe the only solution is to spend the extra money and use Michelin until this problem is sorted? Pain in the back-side. Quote Link to comment Share on other sites More sharing options...
betarick Posted May 20, 2015 Author Report Share Posted May 20, 2015 After 3 Dunlops I have switched to Michelin and problem of going flat while riding as gone!I did like the grip of the new gp but could not trust it anymore. Quote Link to comment Share on other sites More sharing options...
goudrons Posted May 22, 2015 Report Share Posted May 22, 2015 (edited) Didn't someone suggest that a while ago? lol. I'm not one of those conspiracy nuts, but it is odd that these Morad rims only works with Michelin, are the French and Spainish in cahoots? I never had any issues with the older "spokes through" Morad rims, (apart from the obvious leaking issues due to loose spokes and dodgy rim band) just seems the latest solid rims have the issue with impact deflation with IRCs and now it seems Dunlops. As they don't show any signs of leaking "in the garage" it can be a right a*** working out the problem. I don't think it's a limited production problem with either tyre or rim, I first heard grumblings regarding this a few years ago (which I almost ignored due to the fact I didn't own one) I seem to think Trials UK no longer list IRCs and unless my memory has finally given up, when they did list them, the stated they do not fit these Morad rims. I'm sure the problem doesn't exsist with DiD rims, not heard of anyone with a Montesa complain and my old Beta Zero never suffered even though it's back wheel was buckled like a dogs back leg! Edited May 22, 2015 by goudrons Quote Link to comment Share on other sites More sharing options...
Revkev Posted October 19 Report Share Posted October 19 Hi. I'm very new to this but had the same issue of not holding pressure at 6psi. Can I fit an inner tube ? Quote Link to comment Share on other sites More sharing options...
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