daveblackburn Posted March 8, 2021 Report Share Posted March 8, 2021 (edited) HI, I have a 2015 txt280 pro replica. I've been having problems with the rear tire losing pressure. It isn't leaking, but somehow breaking the bead during my ride. I run 5 - 6 psi and can't pinpoint when/where the tire goes flat while riding, but it has to be breaking the bead somehow. I removed the tire, cleaned the bead, checked and cleaned the rim and everything looks good. Rim is straight and true, spokes tensioned and no gouges etc on the bead area. Not the valve stem. I'm running the dunlop 803 and it's in good shape. Any ideas before I just order a new tire and hope it fixes it? Tire holds air indefinitely if I'm not riding. Dave Edited March 8, 2021 by daveblackburn Quote Link to comment Share on other sites More sharing options...
topline620 Posted March 8, 2021 Report Share Posted March 8, 2021 I believe there were some sizing problems with the first batches of Dunlop 803 tyres, I had a new 2016 Sherco with this tyre and it would deflate all the time. I changed to Michelin and never had another problem. I thought the problem with the Dunlops had been sorted now though. Quote Link to comment Share on other sites More sharing options...
daveblackburn Posted March 8, 2021 Author Report Share Posted March 8, 2021 32 minutes ago, topline620 said: I believe there were some sizing problems with the first batches of Dunlop 803 tyres, I had a new 2016 Sherco with this tyre and it would deflate all the time. I changed to Michelin and never had another problem. I thought the problem with the Dunlops had been sorted now though. Hmm. I don't know how old this tire is. Was on the bike when I got it last fall. Quote Link to comment Share on other sites More sharing options...
guy53 Posted March 8, 2021 Report Share Posted March 8, 2021 I ride an 803 on my 2015 ST, no problem Guy Quote Link to comment Share on other sites More sharing options...
pjw123 Posted March 9, 2021 Report Share Posted March 9, 2021 It could be the central rubber sealing strip leaking, losing air & causing tyre to come off rim ?? . Its happened to me. Blow up tyre hard & use soapy water & paintbrush to check for leaks through the spoke holes. Other option is to immerse wheel in a big enough container full of water like you do when checking a tube. If rubber seal shot, it will require replacing. Apico do them. Remove old one & thoroughly remove old sealant (usually Silicon). Ensure spokes all tight & apply a blob of new silicon over each spoke head to seal. Allow to go off. Trial fit new seal ring. (practice) Then run 2 beads of silicon around rim inner well . Now fit rubber seal, previous practice session should have paid off. Finally run another 2 beads of silicon around edge of seal ring. I use Geocell black silicon from Screwfix. Don't use automotive Sikaflex or Tiger seal, as its very difficult to remove & you might need to rebuild your wheel . Works for me. Quote Link to comment Share on other sites More sharing options...
zippy Posted March 10, 2021 Report Share Posted March 10, 2021 15 hours ago, pjw123 said: It could be the central rubber sealing strip leaking, losing air & causing tyre to come off rim ?? . Its happened to me. Blow up tyre hard & use soapy water & paintbrush to check for leaks through the spoke holes. Other option is to immerse wheel in a big enough container full of water like you do when checking a tube. If rubber seal shot, it will require replacing. Apico do them. Remove old one & thoroughly remove old sealant (usually Silicon). Ensure spokes all tight & apply a blob of new silicon over each spoke head to seal. Allow to go off. Trial fit new seal ring. (practice) Then run 2 beads of silicon around rim inner well . Now fit rubber seal, previous practice session should have paid off. Finally run another 2 beads of silicon around edge of seal ring. I use Geocell black silicon from Screwfix. Don't use automotive Sikaflex or Tiger seal, as its very difficult to remove & you might need to rebuild your wheel . Works for me. OP has a 2015. that should have a rear rim with all external spokes. (true tubeless type rim) My 2003 had the rubber seal in the center channel of rim, I replaced it once with a rim band that had the valve stem built in.. Used zero sealants of any kind. Cleaned rim, used a little bit of soapy water when fitting rim band, made sure the rim band fit the channel properly fully under the ridge. Lasted 6 or 7 years until I sold the bike. Quote Link to comment Share on other sites More sharing options...
totty79 Posted March 10, 2021 Report Share Posted March 10, 2021 (edited) On the older bikes with the spoke sealing tape sealant is only needed when the rim is corroded, and using the wrong sealant is a very easy way to cause very rapid and serious corrosion in the first place. Every time someone recommends sealant I think back to some of the messed up wheels I've seen because if it. Edited March 10, 2021 by totty79 1 Quote Link to comment Share on other sites More sharing options...
daveblackburn Posted March 10, 2021 Author Report Share Posted March 10, 2021 Yeah, I have external spokes. I'm going to pick up a new tire today, hopefully that fixes it! I don't see how the rim could possibly be the wrong size. 1 Quote Link to comment Share on other sites More sharing options...
daveblackburn Posted March 29, 2021 Author Report Share Posted March 29, 2021 New tire (same one, dunlop) solved the problem. The one dunlop must have been slightly too large on the bead???? Quote Link to comment Share on other sites More sharing options...
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