Bowie69 Posted May 21, 2018 Share Posted May 21, 2018 Re-found it now back on tablet : Latter comment was aimed at the comparison to the wartime aircraft balloons. As for airing down on tubes, it is a great way to knacker them if travelling distances, as the wear against the inside of the tyre rapidly. You can go to much, much lower pressures on modern, tubeless tyres, not only because of construction, but because they don't have tubes. I would add to the discussion that wider tyres are very likely to be heavier, multiply that by six for an overland and you can end up being quite a lot heavier, which makes everything work harder and break easier, sink easier, and use more fuel. Add lightness and all that 1 Quote Link to comment Share on other sites More sharing options...
deep Posted May 21, 2018 Share Posted May 21, 2018 I have some experience running in sand and completely agree with Eightpot. When I was cruising the Australian deserts, the locals agreed too. Here is the logic as to why a tall, thin tyre is better than a short fat one. Taller gives a shallower angle of attack than shorter - the tyre isn't trying as hard to climb out of it's rut (all tyres sink into the sand a little unless you are talking about a light vehicle with flotation tyres). The more it tries to climb, the more it will naturally dig. Resistance to the tyre comes from how much sand it is pushing out of the way - the wider the tyre, the more sand is getting pushed out. The more sand the tyre is pushing, the more the drag and therefore the more chance of digging in. The plus side to a wider tyre at a given diameter is more contact are = more flotation. You have to balance flotation with drag though. Add it all up and the best bet turns out to be the tallest that doesn't overly compromise clearance/gearing, generally 32-33" on a Land Rover. Because of the drag/clearance problems of an overly wide tyre, you are better off with a 255/85 rather than a 285/75. You might think that a 265/75 is better than a 235/85 but the slight height difference of the latter has proven better than the extra width of the former. I'll also add that, while it's true that a smooth tread pattern greatly reduces the chances of digging, my personal experience is that an aired-down (old school) BFG MT actually digs less than an aired-down BFG AT. That is because, sand being very fine, the AT has more "spades" in its tread! Quote Link to comment Share on other sites More sharing options...
Snagger Posted May 22, 2018 Share Posted May 22, 2018 10 hours ago, Eightpot said: Sorry but that's nonsense! We're discussing standard Land Rover tyre sizes here, so how does that screw up gearing?? And your argument is that taller tyres are worse because they have a larger contact area?! That's what stops you getting stuck... and running 235 tyres is not going to make you roll over on a dune - what makes you roll over on a dune is traversing a dune sideways which you must never do. Anyway I've pitched in my tuppence worth, best to learn through experience anyway - I can't compete with what people have seen on google or what someones mate uses! I've only been round Morocco a few times. And the Sahara, and the Namib, and the Nubian desert, and the Western desert, Skeleton coast and the Jordanian desert, and the Sinai desert, the Jordanian & Syrian deserts, Ubari Sand Sea, Kalahari, Syrian desert, White desert and a couple of others I've forgotten... The discussion wasn't limited to standard sizes as far as I saw. Within normal bounds, though, sure, a lot of what I commented on won't apply. Plenty of folk do fit bigger tyres for desert use, though. Most, from what I have seen. I never said a bigger contact area was a problem - quite the opposite. What I said was that fitting oversize diameter tyres is not a good idea, but 235/85s are standard, so we actually agree on that. I also did not advocate going hugely wide, stating that 255 work well as a compromise between surface area and drag. I also agree on the principle of not driving along dune sideslopes. Plenty of drivers of much modified Jeeps and FJ Cruisers have learned that the hard way here, but those on the super tall tyres suffer more. Quote Link to comment Share on other sites More sharing options...
Eightpot Posted May 22, 2018 Share Posted May 22, 2018 I was only trying to keep it in direct context of the original question, taking a 200tdi 90 on a road trip, it's too big a general subject & definitely one for the pub Tdi Defenders don't have much grunt in reserve in sand, and extra drag is really felt - different matter on a 4.6 'cruiser. Just to go back to the original post also, two weeks isn't much for Morocco, the nicest sand other than the tourist trap at Merzouga, is south of M' Hamid, towards the Algerian border. You need closer to 18 days (if driving from UK) or you won't get to enjoy the rest of the country, which is spectacular. Much of the country has tar nowadays, and most tracks are hard & stoney. A great all round tyre for this stuff is actually the General Grabber TR that LR used to fit, great on sand, gravel and rocks and don't howl on the road. Used to be able to pick them up for peanuts as they don't look fashionable. 1 Quote Link to comment Share on other sites More sharing options...
Aaron681 Posted March 10, 2019 Share Posted March 10, 2019 Just to add two cents. A quick google for sand tyres for landrovers might yield some handy information about who is talking sense here... What you should find is that the original specialist sand tyre was the michelin XS available in 7.00r16 7.50r16 and 9.00r16. Having owned a set of 7.50r16 michelin XS once apon a time. I can tell you that they are a bit sketchy on wet highways. But incredible in soft sand. On an 88" with no real load and pressures of 20psi it would traverse up and down sand dunes no probs.. If you aired down even more they woukd float over very soft ground. vrakking tyres in holland keeps a stock of these and the modern continental equivalent. In 7.50r16 https://www.vrakking-tires.com/16-inch/649-50r16c-continental-hso.html Pirelli uses to make the Dakar Scorpion in 7.00r16 and 7.50r16 i still have a few of these kicking about. Its a shame they seem to be discontinued as they had excellent road manners and the clue as to what their off road prowess was in was in the title. These were the race tyre of choice for many years on the paris/dakar... These sand tyres have a very square profile. They have a tread width the same as the sidewall height. And a low ply rating. 6pr or 8pr max. When aired down the sidewalls deform in a very interesting way.. They bulge from the centre of sidewall as apposed to from the edge of the tread as on many modern all terrain tyres especially p-metric sizes and some LT rated tures. Newer Shinier and Fashionable isn't always better for every requirement.. Serious overland expedition landrover users for years would use a 7.50r16 12ply or even 14 ply Michelin X zigzag patter broad buttress truck pattern tyre. Boring to look at. But rugged. Punture resistant and easy to get of the rim if you do get a punture. Can take the weight of an overloaded expedition vehicle. Are high speed rated for the road. And work well aired down for soft sand. Are tough enough to work well with sand ladders and will give superior performance in deap gumbo mud when fitted with chains, which they can cope better with because of the high ply rating. https://www.vrakking-tires.com/16-inch/748-750r16-michelin-xza-da-new.html https://www.vrakking-tires.com/16-inch/819-22595r16-c-750r16-bridgestone-dueller-tyre.html Tyres are a all a compromise and require intelligent and knowledgeable choice /care and management.. I will try and find a link to an Australian website that goes into all of this stuff in great detail. And compares many different tyre and wheel choices. Needless to say its not without good reason that landrovers standard tyre size for decades was 7.50-16 then 7.50r16 and then laterly its closest metric equivalent 235/85r16.. After all what would landrover and indeed toyoyta know? Side wall ply rating and construction and tread pattern dictate the type of terrain use more than fannying about trying to re invent the wheel with a myriad of different size options.... There is of course more to the story.. Army 88" desert vehicles were fitted with 15" wheels and 9l15 tyres very similar to agricultural implement tyres. The pinkys had 900-15 and 900-16 balloon sand tyres.. These offer specific soft sand performance... But then not much use against sharp stones or thorns... All terrain tyres will work very well for most people in most situations except when extremes of mud or sand are encountered.. There is a great book call the off road and 4 wheel drive book. Worth a good study. https://www.amazon.com/Off-Road-4-Wheel-Drive-Book-Maintaining/dp/1852605448 1 Quote Link to comment Share on other sites More sharing options...
hurbie Posted March 10, 2019 Share Posted March 10, 2019 i've been to marokko ( and senegal , gambia) in a standard discovery , no lift kit etc . fitted BF goodrich MT , yes ...mud terrains ... found no problems with the tyres , we didn't get stuck in the soft sands and no punctures on the rocky patches ... for me they were great tyres to use .... and i found there's more rocks than sand in western-africa Quote Link to comment Share on other sites More sharing options...
Mo Murphy Posted March 10, 2019 Share Posted March 10, 2019 Interesting info Aaron, thanks 👍 Mo Quote Link to comment Share on other sites More sharing options...
Aaron681 Posted March 10, 2019 Share Posted March 10, 2019 Exactly why many people including myself swear by BF Goodrich MT and AT they are worth the money. Again though they are a do it all tyre... So dont expect miracles.. I myself run 255/85r16 BF goorich MT on my 109"and find that they rarley leave me in a bad place and the soft sand performace on the beach is ok when aired down to 15psi. 1 Quote Link to comment Share on other sites More sharing options...
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