weeman Posted April 3, 2008 Share Posted April 3, 2008 I've noticed that one of my tyres looses about 12 psi in three weeks. I've replaced it with the spare and I pump up the (now spare) once a week. There's no sign of any foreign object having pierced the tyre. Do I...... 1. Keep it as the spare and keep pumping it up? 2. Have it repaired? Will such a slow loss of air be detectable by a tyre fitter? If I do get it repaired can anyone recommend a fitter, not to far from me, who I can trust not to butcher my alloys. Thanks Be lucky!! Martin. (CR500's by the way) Link to comment Share on other sites More sharing options...
FTH Posted April 3, 2008 Share Posted April 3, 2008 Reminds me of my first car, a VW beetle- The windscreen wash was powered via compressed air from the spare tyre under the bonnet Obviously when I needed it, it was flat. Could be the valve? Link to comment Share on other sites More sharing options...
shn7 Posted April 3, 2008 Share Posted April 3, 2008 Martin, Don't know anyone local to you but I would suggest an independent fitter rather than the "can't get quicker than a ...." variety. And stay and watch as they do the job. That way you should be able to spot if anything goes wrong. They should be able to find the leak by dunking the wheel in a bath of water. Steve. Sussex (West) AR Not forgetting Percy the Polar Bear Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted April 3, 2008 Share Posted April 3, 2008 Very interesting - one of our locals was discussing this on Tuesday night. He has a CR500 (approx 2 years old) that he uses for road use - it drops from 18psi to 9psi in a week. No discernable leak when immersed in a water butt, but a tyre specialist sprayed the tread with Magic Foamy Tyre Fitters Stuff (MFTFS to you !!) and waited a few minutes - hey presto - bubbles evidencing tread area has a porous band, allowing the air to seep through the carcase over a large area. No doubt on its way back to Avon soon ! Anyone else noticing this ? 7 related photos Link to comment Share on other sites More sharing options...
weeman Posted April 3, 2008 Author Share Posted April 3, 2008 Following those three posts I shall 'dunk' the wheel myself to see if there's an obvious leak, this should highlight any valve problem, FTH. If that 's not successful I shall try to lay my hands on some of SM25T's MFTFS. Meanwhile I will keep looking for a recommended fitter. I agree with you Steve, 'you CAN get better than a quick...... ' Thanks Be lucky!! Martin Link to comment Share on other sites More sharing options...
BadBob Posted April 4, 2008 Share Posted April 4, 2008 I once had this on my motorbike and it eventually turned out to be slight corrosion around the base of the valve. Finally spotted by a switched-on tyre fitter and a clean up and new valve stopped the problem. I assume you've already tried the trick of a dab of saliva in the end of the valve to spot any leakage there? See my Build Cam for progress on the Roadsport Sigma build. Now with photos! Link to comment Share on other sites More sharing options...
gin-fizz-whizz Posted April 4, 2008 Share Posted April 4, 2008 Similar problem on my Audi turned out to be the valve. Worth having the tyre off, revalved and balanced IMO. It's only going to cost you about £6 -£10 and you will also be able to check the inner walls of the tyre for any damage. Blue Roadsport with silver stripe. . . . .it does exactly what it says on the tin! Link to comment Share on other sites More sharing options...
Dazzled Posted April 4, 2008 Share Posted April 4, 2008 I have exactly the same with one of my CR500's. Pressure drops from 18 psi but much more slowly - about 2 psi per week. All the other tyres are fine. Solution is to give it a quick pump of air before i go out each time and on its European jaunts it gets checked over at the first fuel stop of the day. I've kinda got used to it. Link to comment Share on other sites More sharing options...
Steve T Posted April 4, 2008 Share Posted April 4, 2008 Ditto, I have the same problem with 2 of my CR500's, they both lose about 2 psi per week until they get to about 12 psi then they stop. I also give them a pump before each outing. The other 2 remain at 18pis for months. I took the leaky 2 to a tyre place and they immersed them in a soapy bath and changed the valves etc but all to no avail. No sign of any leaks but they still do the same so I gave up. ☹️ Steve Now with DVA Power! 191bhp and 150.9 lbft torque. My Pictures Link to comment Share on other sites More sharing options...
tweeky Posted April 4, 2008 Share Posted April 4, 2008 Dont know if its been said on here but check the valve core tight in the valve ! might just fix it Tweeky In a purple haze Link to comment Share on other sites More sharing options...
w7rren Posted April 4, 2008 Share Posted April 4, 2008 I'll join the queue ! my rear CR500's, they both lose about 2 psi per week .I just top them up . Sure & read some times ago that some alloys are porous. Mark Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted April 4, 2008 Share Posted April 4, 2008 Sounds like CR500s are made of rather porous stuff ? Wonder if there was a bad batch ? Mine are all quite new, and no problems yet. 7 related photos Link to comment Share on other sites More sharing options...
A Ashby Posted April 4, 2008 Share Posted April 4, 2008 I've recently had problems with old alloys not sealing cleanly on the inside rims when new tyres are fitted. The soapy water trick at the tyrefitters finds them pretty quickly and they painted on a sealent to fix it. Happened twice and fixed it that way both times. C7 SSP - Will return Link to comment Share on other sites More sharing options...
Neal H Posted April 4, 2008 Share Posted April 4, 2008 Sounds like a really common problem on CR500's. I have this on one of my rears - it loses 2 or 3 psi per week. Neal. Link to comment Share on other sites More sharing options...
Wrightpayne Posted April 4, 2008 Share Posted April 4, 2008 Friend at work had this on his 3 series beemer - hairline crack in ally rim. Luckily still under warranty 😬 Regards Ian Link to comment Share on other sites More sharing options...
jmalcol1 Posted April 5, 2008 Share Posted April 5, 2008 One of my CR500's looses 2psi a week, check and top it up seems to be the way. John M GK03 EGX SV 22,000 smiles Link to comment Share on other sites More sharing options...
Bumble SV Posted April 7, 2008 Share Posted April 7, 2008 I too have exactly the same problem with one of my CR500s - 18psi to 9psi over about a week but then stops at 9psi and never seems to get any lower I mentioned this to someone at CC (I think) and they said that track tyres somtimes have this problem and that it is "normal" as they are only intended to operate at a set psi for a few hours at a time. Apart from CR500s being not just track tyres, and that CR500s are clearly CC's choice of road tyre, I didn't really believe this. But then I never did anything about it and just continued inflating the tyre each time I take the car out. Interesting comment by Stationary M25 about the pourous band in the tread. Does anyone have a suitable contact at Avon? There seems to be plenty of people with an irritating tyre problem! Roadsport SV - Yellow/Black Stripe Link to comment Share on other sites More sharing options...
Roger Ford Posted April 7, 2008 Share Posted April 7, 2008 Don't know about CR500s specifically, but I do know that motorcycle race tyres lack an "air-barrier" layer in the carcass that you find in road tyres, and hence tend to lose pressure much faster. Given that the CR500 is designed to be extremely light (and is probably expected to be used mainly on-track) it wouldn't surprise me if Avon decided to leave out this air barrier layer to save weight. Link to comment Share on other sites More sharing options...
Ian B Posted April 7, 2008 Share Posted April 7, 2008 I believe Symmo has a contact at coopertire (makers of the Avon CR500), as do I don't have access to my contact details where I am at the moment. Ian - MI 5EVN - Slightly Vider SVelte model 😬 now repainted to match the Autocom headsets 😳 Link to comment Share on other sites More sharing options...
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