It has been a while since I have completed a dedicated Expedition tyre & tube report, but this year warrants the effort. Quite simply we had a lot of trouble when we should not have. The tyres were fine, everyone had Bias fitted, but the tubes on some vehicles let us down very badly. I’ll let the following data tell the full story; see what you think.
We were searching for two watering points that David Carnegie & his party used in 1896. We failed to find them but came up with quite a few other excellent Native Wells & Soaks that more than likely have never been seen by a white-fella. To our knowledge this particular area had not been looked at by modern white travellers, at least we didn’t see any wheel tracks during our journey of 560 kms off-track.
All six participating vehicles were required to fit heavy sidewall tyres, in this case Bias were used exclusively, all but one vehicle had MRF tyres fitted. All tyres were mounted on Split Rims obviously as the tyres won’t fit well on anything else.
Another day at the office |
The following is a run-down of what happened during the expedition to the tyres & particularly the tubes. Over the years we have seen the following problems in small amounts now & again. This year the number of problems in a short space of time was entirely unexpected. Never have I seen such trouble with tubes before. During & after the expedition I spent a great deal of time thinking about what went wrong. See what you think about the stuff below.
NOW before I describe the problems with tubes this year I had better explain how I repair tubes. Over the years my method has evolved so for clarity I had better go through the steps I use in the bush. It is pretty simple & it works on good quality tubes 99% of the time.
Tube prepared for patch, you can see the area cleaned with Liquid Buffer & Scotch-Brite |
Most of the tube problems were tiny splits in the sidewall area which caused slow leaks. There was no damage to the tyre so the only conclusion is that the tube actually breaks & creates a tiny split. All I can think of is that the tubes, particularly the cheap thin varieties, simply don’t handle low pressure where the sidewall area is moving and stretching more than normal. The same tubes when at higher pressures for off-road & on-road don’t have the same problems.
After some research by a colleague it has been revealed that many tubes these days have some amount of recycled rubber in the recipe. Now this recycled rubber could only be tyre rubber as tubes are not recycled to our knowledge. This may explain why modern tubes are not very "rubbery"; by that I mean they don’t stretch well. This may be the cause of the splitting, simply that the tube is not elastic enough & fatigues at low pressure when the stretching & movement is at its worst.
I have over the years refined my fitting technique & experimented with methods to reduce the strain on the tube in the sidewall area. I have found the ingredients for best success are;
The best way to avoid tube splitting at low pressure generally - AVOID USING CHEAP KOREAN / CHINESE TUBES
Tiny split in tube – pretty hard to see isn’t it..... |
Tiny split in the sidewall area on tube stretched a bit to make it visible |
To show this point clearly, look at the table at the bottom of the report;
the vehicles with good quality known tubes (& well fitted) had very little, in fact almost no, trouble.
The splitting of the tubes under the repair patches is a technical mystery and not a problem that is seen by the experts. We know this because before writing this report a colleague & I spoke to a few known experts in the tyre & tyre repair industries. They had not heard of tubes splitting under patches at low pressure in a 4WD situation. So we are on our own.
Inspecting the 4 tubes that split under the patch on the expedition it was noticeable that on some the patches hadn’t stuck really well & others the patch did stick on properly.
I’ve broken the problem into a few possibilities;
Patch lifting from Chinese tube. With good preparation & technique this shouldn’t happen, but it does |
Removed some of the same patch from the same Chinese tube & you can see that some of the patch
didn’t bond well (black area) & that some of the patch had bonded well (orange bit). |
Another failed tube patch (it tore in half getting it off), but this one has pretty consistent colouration,
meaning that it seems to have bonded OK, but it still allowed the tube to continue splitting underneath it |
The solution to this problem is easy. Don’t run at really low pressures for weeks at a time. Of course we can’t do that on our off-track expeditions. So, I’m left with experimenting with how to solve this problem. To cut a long story short I have two main options that I can think of to try & stop the tube splitting under the patch. Both methods are trying to restrict the stretching of the tube. I’ll try both next year & see what happens.
An excellent result for the tyres, better than expected in fact; three of the stakes were on the lead vehicle. All of them were repaired and put back to work as usual during off-track expeditions.
One of the 4 staked tyres, pretty standard. |
Vehicle | Tyres | Date | Cause (& size) | Position | Comments |
---|---|---|---|---|---|
Land Rover 130 Defender NSW 5 flat tyres |
Bias - 14 Ply MRF "Super Miler" 7.50-16 Bridgestone tubes (fitted by Mick) |
17/8 | Tread stake – 5mm | Front left | B8 mushroom & #5 tube patch |
20/8 | Looked like tiny tube rub..... | Front right | #5 tube patch ----- (poor fitting – my fault) | ||
21/8 | Shoulder stake – 10mm | Rear right | No.5 tyre patch & #4 tube patch | ||
28/8 | Tube split under patch | Front right | New tube fitted | ||
29/8 | SW/shoulder Stake – 3mm | Front left | No.3 tyre patch & #5 tube patch | ||
Toyota V8 Utility WA 9 flat tyres |
Bias Kenda & MRF 7.50-16 Korean & Chinese tubes Customer did all but two of the fitting jobs |
15/8 | Tube hole in sidewall area | Rear right | #3 tube patch |
15/8 | Tube hole in sidewall area | Rear left | #3 tube patch | ||
16/8 | Tube split under patch | Rear ? | New tube (Buff off old patch & #5 tube patch |
||
16/8 | Tube hole in sidewall area | Rear ? | #3 tube patch | ||
21/8 | 3 tube holes in sidewall area | Rear left | Customer did repairs | ||
22/8 | Tread stake – 10mm | Front ? | No.3 tyre patch & #4 tube patch | ||
22/8 | Tube split under patch | Rear ? | Spare tube fitted ? | ||
27/8 | Tube holes in sidewall area | Rear right | Fitted new Bridgestone tube myself | ||
27/8 | Tube holes in sidewall area | Rear left | Fitted new Bridgestone tube myself (No more problems after this) |
||
Toyota V8 Utility SA 5 flat tyres |
Bias - 14 Ply MRF "Super Miler" 7.50-16 Korean tubes |
22/8 | Tube hole in sidewall area | Rear left | #4 tube patch |
22/8 | 3 tube holes in sidewall area | Rear right | Fitted spare tube | ||
23/8 | Tube split under patch | Rear right | |||
27/8 | Unknown cause | ? | Heard about flat tyre on UHF after vehicle left trip for mechanical reasons | ||
27/8 | Unknown cause | ? | |||
Nissan GU Patrol ute QLD 1 flat tyre |
Bias - 14 Ply MRF "Super Miler" 7.50-16 Korean tubes (fitted by Mick) |
27/8 | Slow leak - unknown cause | Front left | Put spare on & vehicle left trip due to mechanical problems before tyre was repaired |
Toyota 78 Troopy WA ½ flat tyre |
Bias - 14 Ply MRF "Super Miler" 7.50-16 TOYO tubes (refitted by Mick) |
18/8 | Shoulder stake – 2mm No damage to tube |
Front right | Pulled apart to clean & silicone early in trip, stake found in tyre, but tyre not flat. UP6 on tyre – nothing needed on tube |
Ford Ranger Dual Cab ute QLD |
Bias MRF "Super Miler" 7.00-16 Bridgestone tubes |
No punctures or trouble recorded |
I’ll include a brief overview of these problems in the 2016 Tyre & Tube Report & include some further conclusions & developments.
We’ll see if we can have a better run next year.......
Regards,
Mick Hutton
Copyright : December 2016
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