Thin tyres v Wide tyres on sand

Submitted: Thursday, Jul 22, 2004 at 16:55
ThreadID: 14912 Views:8331 Replies:15 FollowUps:11
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I have a hilux with standard split rims & tyres. Some folks say I should upgrade to wider tyres for the sand, others say wide tyres just "push" more sand and to stick with the standard ones at a lower pressure. What are the myths and facts.
Thanks in advance!
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Reply By: Squid - Thursday, Jul 22, 2004 at 17:05

Thursday, Jul 22, 2004 at 17:05
I still have skinnies on my hilux and have never had a problem on the sand. Been to Stockton a couple of times when the sand was very soft and never required snatching. Just keep your pressure down and you'll be right.

Cheers
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Reply By: Ian(Qld) - Thursday, Jul 22, 2004 at 18:09

Thursday, Jul 22, 2004 at 18:09
I've had skinny tyres and fat tyres over the years with different 4x4. I now have a troop carrier. Until last weekend I have never done a direct comparison between 750x16 Road Grippers on 5.5 inch split rims (standard fitting for 78 series troopy) and BF AT 265x16 on 8inch 100 series rims on the same vehicle in the same sand. I had a preference for the split rims for the all round bush combination, ease of changing tyres etc.

Last weekend I fitted a set of BF ATs and went back to Bribie Island to test where I had previous difficulty. Set at 25psi was amazed at the difference. Probably half the engine effort. I deliberately went into the softest sand I could find and was left very impressed.
The only downside is changing the tyres with R&R beadbreaker I found it impossible to get the bead to set so I could pump them up. That leaves me with a worry of changing them in the bush. The local tyre man gave me some tips on how to get the bead to stick but I haven't had the oppotunity to try that out yet.
So, yes you can get where you want with skinny split rims but you can further with less effort with more suitable fatter tyres.
Just my experience.
egards
Ian
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Follow Up By: member-skippyking - Thursday, Jul 22, 2004 at 20:22

Thursday, Jul 22, 2004 at 20:22
Ian,

tyres set at 25psi.....can't have been very soft sand. Thats almost dirt road pressures. Should be starting at 15psi, 18 max.

SK
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Follow Up By: Ian(Qld) - Thursday, Jul 22, 2004 at 20:59

Thursday, Jul 22, 2004 at 20:59
skippyking,

I remember Double Island Point in the days before board walks and using 8psi on 55 Tojo and using Honda Odessy tyres on a camper van at 3psi. I have experienced "soft sand".
I was offering the experience of the same 3 tonne vehicle, same sand conditions, different tyre/rim setups. The result was chalk and chesse. The decrease in engine effort was a pleasure.
Ian
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Follow Up By: member-skippyking - Thursday, Jul 22, 2004 at 21:27

Thursday, Jul 22, 2004 at 21:27
Ian, not having a go just replying to what was written in your original post. I still say that at 25psi you can't have been in 'soft sand'. In all the sand driving I've done no-one gets far at 25psi. They also wreak havoc on the tracks that others have to follow in. You do know what soft is though by your follow-up and I have been in that sort of situation down here on the south coast of WA where we had to go to 5 to get out of trouble.

If you had done your comparison on the same day I would be happy to concede to your test, but differing conditions in humidity, temperature, rainfall make a HUGE difference to driving conditions.
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Follow Up By: Greg Harewood - Thursday, Jul 22, 2004 at 21:37

Thursday, Jul 22, 2004 at 21:37
skippyking,
As others have pointed out (and me before in other posts) - its not the width that is important but the lenght of the front to back contact..thats why letting you tyres down in soft sand (fat or skinny) works great - it increases the actual back/front area to which drive force is being delivered greatly...the expansion sideways is of no advantage. While you may have found your "fat" tyres better how do you know it was due to the extra width? There are a number of other variables besided the width of your tyres that you have not considered - maybe they have a longer front to back contact area at that pressure - it pays to be a tad more scientific in this day and age - old wives tales (eg fat tyres are better in sand simply because theyre wider) just dont cut it anymore.
Im not saying you didnt find the fat tyres better - Im saying it wasnt due to their width compared to your skinnies.
Cheers
Greg
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Follow Up By: Greg Harewood - Thursday, Jul 22, 2004 at 21:39

Thursday, Jul 22, 2004 at 21:39
Sorry last post was directed at Ians comments - not the very erudite skippking
My apologies
Cheers
Greg
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Follow Up By: Ian(Qld) - Thursday, Jul 22, 2004 at 21:55

Thursday, Jul 22, 2004 at 21:55
More info.
Original tyre on split rim 750 75 16, which I think is equivalent to 225 or 235 on a 5.5 rim. The replacement 265 75 16 on an 8 inch rim. Total tyre circumference on both was equal as the speedo was checked by GPS before and after comparing speedo speed to GPS speed. I can only conclude that the length would have been the same and width increased by 50%.
The whole ride on sand was chalk and cheese.
I've been there and done that in the past and have a much more conservative approach to obstacles than I did 30 years ago. I like the low powered approach compared to the big rush at the object these days.
Just my experience
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Follow Up By: Greg Harewood - Thursday, Jul 22, 2004 at 23:43

Thursday, Jul 22, 2004 at 23:43
No worries Ian - when next doing a tyre assessment keep in mind the other variables that are often overlooked...some are - variations in weight of vehicle (same tyre pressures - different load will give different results). Flexibility of tyres/ply rating will effect how a different tyres behave at different pressures/loads. Wets sand - dry sand - same location different time of year, different traffic load....all change the result with same tyres. Driver technique I suppose must be important also...My experience is that tyre pressures are the only matter for consideration when driving on sand. It doesnt matter that much what tyres you are using - fat or skinny - been bogged with both:)

Cheers
Greg
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Follow Up By: Peter Guy - Friday, Jul 23, 2004 at 18:14

Friday, Jul 23, 2004 at 18:14
Ian on the large 4 wheel drive tyres I have yet to see anybody "set the bead" when changiging tyres in the bush with just tyre pliers and levers.
On normal cars with standard tyres you could use strong rope or light chain to criss-cross around the tyre after it is fitted back onto the rim and when tightening the rpoe/chain it has the effect of squeezing /pushing the bead onto the rim creating a seal then enabling pumped air to build pressure and pop the bead into position.
The 4 WD tyres are just too big and not pliable enough for this method to work easily. You can hammer the bead into position when the first half of the tyre is on the rim and try to get the second half in position with the tyre levers - but this is hit and miss.
The easy solution is to carry spare tubes. So If the tyre punctures again the tube is easier to fix and you just keep inflating the tube until the tyre bead pops onto the rim.
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Reply By: Member - KG (QLD) - Thursday, Jul 22, 2004 at 19:31

Thursday, Jul 22, 2004 at 19:31
ditch those poxy cheese cutters NOW!!! :)
yeah theyre great in the bush if you wanna repair a tyre... but i mean really - how many flats have you had that you couldnt repair ON the rim? maybe i don't get out enough :(

and Willem I know you're a split rim fan... as was my old man (probably for similar reasons... simple, dependable, one less thing to go wrong, etc - same reason he hated electric windows, electronic dashes... anyway - im getting away from the point)

from a practicality / repair point of view they are great... from a looks point of view they are ordinary.

as far as how they perform in the wild... i only did some light sand work with the old splits before i switched to the (slightly) wider 235's.... the 235's seem to bag out better at higher pressures - if you're prepared to go below 18 psi you get good results with the splits... with the 235's i can sit on about 22psi and get a similar contact patch.

but then again... i have read others on here post that they live in the desert and they run splits because they perform BETTER on the sand than the fats!!!

no doubt you'll get a lot of conflicting views on this topic... something you need to weigh up for yourself i guess.

cheers!

KG
AnswerID: 69092

Follow Up By: Gajm (VIC) - Thursday, Jul 22, 2004 at 22:43

Thursday, Jul 22, 2004 at 22:43
"from a looks point of view"?? says who...and who cares?

When I was looking to buy a CT, I asked one manufacturer if I could get rid of the supplied wide sunrasia tyres and wheels, and fit 750/16's the same as what is on the towing vehicle....he said "yeah...you could, but it would look crap" I said I don't give a damn what it looks like, I want the same wheels and tyres all around. He told me again "I could do it, but I'm telling you, it looks Sh*t house".

I didn't bother getting a CT from him because I figured he didn't know squat about what they are used for. I don't care how good the bloody thing looks if I am stuck on the side of the road in the middle of no where. Just who are we trying to impress?
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Follow Up By: member-skippyking - Friday, Jul 23, 2004 at 12:11

Friday, Jul 23, 2004 at 12:11
Spot on Gajm!! (thumbs up)
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Reply By: Bonz (Vic) - Thursday, Jul 22, 2004 at 20:17

Thursday, Jul 22, 2004 at 20:17
Its not the width but the length hats inportant so the skinnies would do the job just like the fats. Whatever you reckons a fair thing, although 235/85's are a great thin/fat compromose, had em on my Mav and they were great.
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Reply By: member-skippyking - Thursday, Jul 22, 2004 at 20:34

Thursday, Jul 22, 2004 at 20:34
Bonz is on the right track here. When you deflate your tyre, sure the sidewalls 'bag' out. But your tread doesn't get any wider and it's not your sidewalls thats keeping you up, it's the tread 'flattening' out front to back. You are getting a longer contact patch, not a wider one.

As to skinny or fat? Well, it's debateable but IMO your vehicle works a bit harder with fats as it IS pushing a little hill of sand in front of the tyre and the wider the tyre, the wider the hill it is trying to climb over. But the difference is probably so small as to be "a bee's d!ck of **** all".

akarosco, stick with your skinnies for the cost factor of changing over to wider rims and tyres.

SK
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Reply By: Crackles - Thursday, Jul 22, 2004 at 21:46

Thursday, Jul 22, 2004 at 21:46
After running fat & skinny tyres on 3 different cars I found very little difference between them. The narrow ones may sink deeper but push a small amount of sand in front. The wide tyres float higher but the hill of sand in front is also wider.
If I had to pick, the fats would have a slight advantage in some sand conditions although I prefer the bulldozer approach.(long & skinny) Cheers Craig...........
AnswerID: 69138

Reply By: Eric Experience. - Thursday, Jul 22, 2004 at 22:01

Thursday, Jul 22, 2004 at 22:01
akarosco.
750's are the go on sand. as stated by others, I was watching a documentary on the Sahara desert, there were 2 vehicles, one with 750 and the other had wide 15" tyres,the one with the 750's was towing the wide tyre machine over the dunes.You dont get dryer sand than the sahara. Eric.
AnswerID: 69143

Reply By: Member- Rox - Thursday, Jul 22, 2004 at 23:51

Thursday, Jul 22, 2004 at 23:51
I may be the only member here to run fats 275/75/16 and standard 750 / 5.5 skinnies on the same beach the same day, the time difference was changine the tyres in the car park. Why??? I had to settle this arguement for my self. The results the skinnies were a little bit slipery on the back end. thats it! it went just as far. Test beach was Tims thicket WA Tyer presure was same 15-18 i think but both set by Staun tyre deflatores.

My experance on a diff beach.....I pulled my camper @ christmas over river mouth @ Pallingup ct weight was 750+ I got through on 12-15 psi all round. Coming the other way was a Hilux towing a boat being pulled by another 4wd, the hilux had fats.

Post 9117 said I was stupid but my reply I saved as I couldnt load it was
"My view is that you are no better off in the pocket !!!!!!!!!!!!!!!!!! "
Quiet the contra, I needed tyres and rims for my new camper as it uses less fuel rolling rather than scraping away the metal, lol. New set of fats was $1200 and I don't think they performed well on the beach, so why buy more of what you don't like???
MY $ MY choice I choose to have 2 spares on the CT (extra spare was < $200) as apposed to $2000+tyre/rim for a duel wheel carrier on 4wd (you do the maths)
Ps I think long term Round oz next year 3lt better of for every 100kms (30,000 km,s x 3%saving = $900 saving) (wow I think they now add up to FREE) and I can have up to 3 flats before I need to fix 1 up in the cool of the day not the heat!!!!
PPS everybody has diff needs

I should + the skinnies are 3 kms better or the fats were 3kms error (gps)

Hope this helps.
AnswerID: 69155

Follow Up By: member-skippyking - Friday, Jul 23, 2004 at 12:31

Friday, Jul 23, 2004 at 12:31
Rox,

went over the Pallinup River mouth a few months back and it was the softest stuff I've seen for a few years and it was damp and cool at the time.

Nice spot though.
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Reply By: Member - Pesty (SA) - Thursday, Jul 22, 2004 at 23:54

Thursday, Jul 22, 2004 at 23:54
Go with the Wider tyre as they give better flowtation as the print is almost the same as a skinny but twice as wide. The 4by will flow along the sand with less effort in my experience.
AnswerID: 69157

Reply By: Member - Brian (Gold Coast) - Friday, Jul 23, 2004 at 09:37

Friday, Jul 23, 2004 at 09:37
33 X 12.5 Muddies on 15 X 8 Sunraysia's didn't stop us on Fraser Island. More than once. Anywhere! Including the tracks that we were advised to stay away from 'cos they're too soft, (by people on this forum amongst others!)..... Indian Head, Northern Tourist Track, Wathumba Rd et al..... at 22 psi as well, and no track damage 'cos no wheel spin.
Just my 2c worth
Not trying to inflame a tyre war, just relating what works for us.
:-))
AnswerID: 69200

Reply By: Waynepd (NSW) - Friday, Jul 23, 2004 at 10:01

Friday, Jul 23, 2004 at 10:01
I seem to remember a comparo done between skinnies and wides in a 4wd mag last year (i think it was) and the wide tyres won in the overall sand, mud and rock traction stakes based on better flotation as mentioned in a reply above.

Sorry i can't remember which mag but i do read 4wd monthly more than any of the others so it could have been in there. It was heralded as the definitve wide vs skinny tyre test or something similar.

AnswerID: 69208

Reply By: Truckster (Vic) - Friday, Jul 23, 2004 at 10:21

Friday, Jul 23, 2004 at 10:21
Once again, lots of variables..

Tire conditions, suspension, weight of car, weight of drivers right foot, weather conditions....

We did Robe last Oct with the club, 2 convoys of 8. All with 10.5/12.5's, and only once did we strike an issue, that was an unexpected washout, one bloke stood on the picks and car behidn nearly ran up his ginger. So we had 2 stuck.

But as for driving around, all running 18psi, not an issue. One flat tire on a rocky shelf, but could have been driver issues.. ;)

There are arguements for both.
Thin will cut in and dig, wide will push etc..

Trial and personal preference really. I havent had cheeze cutters, so cant comment, but 90% of 4b's that we saw at Robe had 10.5s at least.

YMMV
AnswerID: 69214

Reply By: Member - Rohan K - Friday, Jul 23, 2004 at 13:36

Friday, Jul 23, 2004 at 13:36
akarosco have a read of this tire bible

Scroll down about 2/3 of the page and you'll find a bit on contact patches.

Generally on sand, if the contact area were the same, skinny and long is better than wide and short. This is true because the narrower leading edge creates a small area of sand build up over which it must climb (it's like a mini hill being constantly created in front of the tyre as it pushes through the sand. It has nothing to do with floatation (remember the contact area is the same) but the vehicle will not work as hard to maintain forward motion so it will use less fuel.

One problem with the 750R16 on split rims though is that because of their construction you cannot safely reduce pressures to the same degree that you can with a radial on a JJ rim. This means that you you are more likely to be able to achieve a bigger contact area with a radial and therefore achieve better flotation.

Flotation depends entirly upon the contact surface area and the weight of the vehicle. Unfortunately, it is almost impossible to determine what the contact area would be for any given tyre at any given pressure without doing a test similar to that doe by 4x4 Monthly some time ago (where they fitted different tyres at different pressures to the same vehicle, jacked the vehicle up and inked the tyres and then let it down again onto pieces of paper to get a "foot print").

Sorry :)
AnswerID: 69246

Reply By: Member - Jeff M (WA) - Friday, Jul 23, 2004 at 15:55

Friday, Jul 23, 2004 at 15:55
I got bagged out last time I made a comment about wide tyres on this forum, however I stick to my guns, I have had skinny tyres and I've had wide tyres, there is a lot of sand here in WA, and wide all the way mate.
But don't be fooled, wide does not mean you don't let your pressures down, you let them down the same amount as you would with skinny tyres, otherwise your wasting your time.
AnswerID: 69258

Reply By: Glenno - Saturday, Jul 24, 2004 at 15:21

Saturday, Jul 24, 2004 at 15:21
I reckon I get better traction on Sand when I let my tyres down from 25psi to 20psi on the Sand. Whether it was on the original HT's or Cooper ST's, the lower pressure makes big difference.

Currently runnning 30*9.5 Cooper ST's - run them at 20psi and they go anywhere on Sand.

Cheers,

Glenn.
AnswerID: 69406

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