Tire questions for the BIG TRUCK boys

[apexcamper]

I summed up all my questions at the bottom.

I have an opportunity to get a set of Michelin XL 14.5R20...ex military, almost new, super low mileage.

They even have split rims to match, but of course this means that they are tubed tires. My limited knowledge says to me that tubed tires are better, in that you can air them down more without the need for bead-lock rims or the fear of breaking a bead. It also seems to me that it is easy to carry several extra tubes and tube repair kits in lieu of 2 or 3 spare tires. Of course, this thought process flies in the face of the fact that no one runs tubed tires.

Ultimately the deal will probably end up being affordible enough that I can't pass it up (currently running skinny 10.5R22.5 and dual rears), but this is a great opportunity to start a discussion and I need the "what to watch for" list.

I am also confused as to why 14.00R20 tires are taller than 14.5R20 tires. I was under the impression that military tires used a standard 80% ratio, meaning the 14.5 should be taller than the 14.00.

If there are threads already discussing this stuff, links to answers would be great

What are the down sides to tubed tires/split rims?

Why are 14.00R20 tires taller than 14.5R20 tires?

 

[Iain_U1250]

A 14.00R20 is a 50" tyre - it is 14" wide - 100% aspect ratio. A 14.5R20 is 14.5" with an 80% aspect ratio and is a 45" high tyre, in modern terms it is a 365/80R20. The other size commonly available in ex military is the 395/85R20 which is a 48" high tyre - you can pick these up in the USA for around $150 in "almost new" They are pretty heavy, but have a high load rating.

Split rims are pretty heavy, that's the main downside in my opinion, tyres are easier to get on and off the rims is the main advantage.

As far as tube vs tubeless - lots of debate, but I don't think there is much difference in the long run, each has advantages. I run internal beadlocks on my 365/80R20 Continental MPT81's can lower the air pressure down to 5 PSI if I have to without de-beading - can't do that with a tube tyre.

 

[LukeH]

Hi there,
Tubed tyres are perceived to be easier to deal with when you’re far from everything because of the tight bead issue.
Breaking the bead is hard work on a tubeless, but is possible. There are accessories to do it with these days, I know tyre pliers do a 20 inch version of their bead breaker.
But I believe the greater worry is getting a tubeless tyre seated again after you’ve repaired it. Huge amounts of air are required rapidly.

Tubed tyres have the advantage of inflating whatever air is available.
They are obviously heavier and are more prone to punctures. I defy anyone to change a 20 inch tube in a dry environment leaving NO sand or grit between the tyre and the tube. If the tube is good quality the grains will simply embed and that’s the end of it…. Until you air down.
The tube and tyre move against each other and if there is grit then it will eventually penetrate. If there is no grit the movement will go on for longer, and the tube will heat up. If you already have a patch on the tube that’s what will come unstuck first in the heat (often the hardest puncture to find, and also difficult to clean off an old patch); the final outcome of heat and wire fatigue in the tyre casing is the blowout.
Running at low pressures can be expensive.

Whatever, if the offer you have is too good to refuse, go with the tubes. In developing countries you’ll always find someone who can vulcanise a patch on, and that’s more solid than the Rema Tip top glued on patches.

Sorry I can’t answer the height question. Do check the load ratings of the 14.5 tyres, on some models they are surprisingly lower than the 14” versions.

There is, however a drawback that could cause you some problems:
You’ve bought the exact truck I was interested in when I was looking for one. One of the reasons I didn’t snap it out of Phillipp’s yard was because I read somewhere on the net that the 110-17 has upgraded (larger) brakes over its older brother the 160-11 (or 110-16 – Iveco and Magirus had very similar denominations for the same truck).
The older vehicle runs 20 inch rims but never came with a double cab.
I wanted a double cab on 20 inch wheels.
Nobody could answer me when I asked if the 20 inch rims fitted over the newer upgraded front brakes.
On the rear it’s not an issue because the single rear wheel would have the dish the other way round; you just don’t mount the inner wheel.

Without a committed answer from Phillipp or the rest of the internet, I didn’t want to commit to buying that truck.
Just as well in the end because now you’ve been able to take it on.


I even thought of buying it and a 11-160 and swapping the axles to be sure to have the right brakes, then selling off the single cab truck with “road” axles and wheels.

So before you take the plunge, make sure they go over the brakes. Let us know, then I’ll know whether to kick myself! It is a nice clean truck and I really fancied it….


Hey Iain, what bead locks are you using?

 

[Iain_U1250]

I had Staun make custom 20" set for the MPT81's and fit them, their manufacturing centre was just down the road from me. Unfortunately they went bust, but the guy who made the original Staun beadlocks has set up shop in Melbourne, under "Second Air Beadlocks" maybe he might be interested in making some for 20" rims again.

 

[blowfly]

I have a Iveco Daily 55S17W 4x4 expedition vehicle built by Traveltrucks in Brisbane(QLD)
I want to put a proper CTIS on the Iveco (no external air lines).
Currently running 37x13.5R17 tyres on WalkerEvans Racing wheels but will change in future. Would like to go to 20inch wheels and narrower tyres.
Trying source CTIS equipped wheel hubs or full replacement axles like Unimog.
Anyone have any ideas?
Thanks in advance.

 

[charlieaarons]

A 14.00R20 is a 50" tyre - it is 14" wide - 100% aspect ratio. A 14.5R20 is 14.5" with an 80% aspect ratio and is a 45" high tyre, in modern terms it is a 365/80R20. The other size commonly available in ex military is the 395/85R20 which is a 48" high tyre - you can pick these up in the USA for around $150 in "almost new" They are pretty heavy, but have a high load rating.

Split rims are pretty heavy, that's the main downside in my opinion, tyres are easier to get on and off the rims is the main advantage.

As far as tube vs tubeless - lots of debate, but I don't think there is much difference in the long run, each has advantages. I run internal beadlocks on my 365/80R20 Continental MPT81's can lower the air pressure down to 5 PSI if I have to without de-beading - can't do that with a tube tyre.

Actually most 14.00R20 are 49.5”, 14.5R20 (365/80R20) 43.1”, and 395/85R20 46.6”.

 

[charlieaarons]

I have a Iveco Daily 55S17W 4x4 expedition vehicle built by Traveltrucks in Brisbane(QLD)
I want to put a proper CTIS on the Iveco (no external air lines).
Currently running 37x13.5R17 tyres on WalkerEvans Racing wheels but will change in future. Would like to go to 20inch wheels and narrower tyres.
Trying source CTIS equipped wheel hubs or full replacement axles like Unimog.
Anyone have any ideas?
Thanks in advance.

There’s been several outfits go in and out of business over the last 15 years (that means parts could be a big problem) that will sell you portal hubs for various axles. With gearing increase of 1.25-1.50. Over the years they all advertise “ready for CTIS”.
In the States they focus on Dana axles, but I’ve also seen conversions for Landcruiser etc.
Be prepared to spend lots of $$$$.
Maybe you should buy a new Unimog. At least they sell new ones in Oz, and you’re guaranteed long term parts access.
And if you do portals, do what I did with my U500: install a temperature monitoring system (I have one made by Atlas for Unimogs) for the portals.
Use Google.