Leaking CH701 / CH750 / CH801 tires

I think most builders have at least one slow leak tire on their aircraft. On mine its the nose gear tire, it leaks down over a couple weeks while the mains have never leaked. I was thinking about putting tubes in the tires, but that adds extra cost and weight (I assume that is why tubes are not included in the kit?). A fellow builder Bob Stuart (CH701 plans only) suggested removing the valve stem and injecting (syringe) 5 - 10 cc of anti-freeze then installing the stem and inflating the leaky tire. The anti-freeze helps to seal the low pressure tire / rim. Bob claims its a trick used around the farm for years. I will give this a try on the nose tire before I install a tube.

Any thoughts?




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Comment by Jonathan Porter on May 9, 2011 at 6:24pm
My 2c worth.... regular soap (sunlight and green slime) is full of salt - that can cause corrosion.  Oil (and probably anit-freeze) thin and seep over time.  IF you go to the tyre shop they use a 'tyre solution' it is white and slimy.  Even here in Africa, when we asked they filled a small water bottle with the stuff for free.  We mounted the tyres and had one problem in 6 tyres.  Took it apart and refitted it up with the O ring and it was fine... probably a pinched O ring...  The issue with run flat products is that they need to be run at at least 20mph for several minutes to spread around - they need centrifugal force - and they coat the tyre not the rims and centre - if it sits in a spot it can cause unbalancing of the wheel.  BUT whatever works for you!
Comment by Harmen van der Velden on May 8, 2011 at 5:46am

It may not be the right thing to do , but I used one can of "fix a flat" shared between the 3 tires. now have to bring tires up to pressure (12psi) about twice a year. so far 130 hrs in 2 years and all is fine.


Comment by Thomas Jackson on May 6, 2011 at 1:56pm

Hey Bob,

I have used Green Slime for years on many different small tubeless tires and it works well. I have not had that problem with my 701, since it is still land locked. With the Green Slime (available at most auto stores) it works best when you rotate the tire and rim in all direction to spread the GS especially around the rim area.


Comment by Bob McDonald on May 6, 2011 at 1:24pm
I have seen an ATV spin the rim inside the tire...and that tears out the tubes valve stem ! But I don't think that is possible with aircraft tires in the LSA category? Its simply a added weight & $ dollar cost for tire tubes.
Comment by Andre Levesque on May 6, 2011 at 8:36am


What's the issue with using tubes? Other than weight. I researched the differences in using Tubeless vs Tube aircraft tires and there are many opinions. But it seems like they see tubes as OLD technology.

Maybe with many landings the tubes one would put stress on the valve and eventually puncture?

But yes, a flat in the woods...you are right is not that good. -:_) 

On my ATV's they are tubeless with 4 lbs of air and let me tell ya...they take a beating and they don't lose air.

The 2 halves hub seems to be the issue with that O-ring. Can't we get  ONE piece wheel hubs??  That would solve the issue.harder to put the tire on maybe..but worth it I guess. Do they exist?


Comment by Bob McDonald on May 6, 2011 at 3:02am
I "lubed" the "O" ring with Sunlight soap on assembly. Like said two of my tires & rims are perfect, the nose only a minor leak but it is a pain-in-the-ass type of issue. I think Ralph might be onto some thing... these are cheap quality tires. Bob Stuarts tire developed a crack along the tread, in the middle of the tire just sitting in the hangar. A flat in the back country can strand you far from your nice warm bed !
Comment by Ralph Sanson on May 6, 2011 at 2:24am

I had a leak in left main for a few months, tried using the can of tyre goo (sparingly, as I thought it was around the tubeless valvestem) took about 6 weeks to go soft. Removed the tyre and fitted a tube.

Leak was identified as thin spot in the middle of the tread.

Eventually I expect to fit tubes to all of them. Now carry a spare tube. The writing on the tyre sidewall says "tube type"





Comment by Andre Levesque on May 5, 2011 at 10:30pm

To use a tubeless tire the rim must be sealed . Airliners use two piece rims that are sealed between to two halves. 

Small wheel rims are also made the same way as larger tubeless rims are, they split in half, but they are not sealed with a rubber ring and have a hole in the outer rim to allow the tube inflation stem to stick through.

That's what the antifreeze does. But I've seen a spray can at Canadian tire for that purpose. made for wheels made of two halves. If I find the product I'll post it here.

Comment by Bill Alexander on May 5, 2011 at 9:08pm
You are not alone, it's the left main for me. I even took back apart and added RTV all around the O ring. It seemed to help, but stll need to add air about every 10 days or so. The anti freeze sounds like a worth while try.
Comment by Joe Harrington on May 5, 2011 at 5:51pm

Hi Bob,

Did you tire lube the o-ring when you installed it? I have also heard that you can try deflating the tire, then loosen off the wheel-half bolts evenly a little bit (a turn or two) then inflate to a low pressure (a pound or two) and then tighten up the wheel bolts evenly. This idea is to "set" the o-ring in a little and squish it between the wheel halves. No experience with this myself but made sense to me.

Good Luck,


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