Tyre pressure for split rims

Submitted: Monday, Jun 05, 2006 at 09:56
ThreadID: 34624 Views:7231 Replies:8 FollowUps:10
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Hi All,
I have a set of split rims for our 78 series Landcruiser. I've done a fair bit of four wheel driving with plain steel rims but are new to split rims. I have heard from various people that you can have problems with split rims at low pressues in sand ie lots of flats. Is this true?

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Reply By: chump_boy - Monday, Jun 05, 2006 at 10:04

Monday, Jun 05, 2006 at 10:04

I think the tubes can slip round the rim, and tear off the valve if the pressure are too low. Also, I guess sand could get inbetween the tube and the rim or the tyre, causing problems later on.

My 105 series has splits, and I have driven on Stockton on about 12 psi no probs. Obviously I am not doing doughnuts or anything, but the old girl just floats along.

In the 12 months or so we've had her, we haven't had a single flat.

You'll probably enjoy the fuel economy of the narrow tyres as well. I rekon you'll save about 2L/100km if you keep them pretty well aired up (we sit anywhere between 40 and 50psi, depending on where we are driving).



AnswerID: 176768

Follow Up By: Steve63 - Monday, Jun 05, 2006 at 10:22

Monday, Jun 05, 2006 at 10:22
Thanks for the info Chump. 2L/100km sounds good. I currently get 11L/100km 9 would be great. Can I ask what tyres you are running?

FollowupID: 432818

Reply By: chump_boy - Monday, Jun 05, 2006 at 10:29

Monday, Jun 05, 2006 at 10:29
lol - gees - I get around 11 or so now. It changes, depending on what we are doing. Not sure if you would get down to 9 - that would be brilliant! I am only guessing with the 2L/100km - it seems that most people that run fat tyres get around 13L/100km on their 105 Series - I could be wrong (wouldn't be the first time...)

Mine are the good old 7.5 16 things, dessert duelers. They have shown little wear in the past 15k kms, so we are pretty happy with them.

We will change to 235/85 if we can when the time comes, simply to get a little more height, and increase the gearing a little (it would be nice to be doing more than 50 in bloody fourth gear.....lol).



AnswerID: 176775

Follow Up By: Steve63 - Monday, Jun 05, 2006 at 10:51

Monday, Jun 05, 2006 at 10:51
Sounds like the same tyres that what are on our splits. I have yet to put on the splits. The wife did most of the negotiating in the purchase of the vehicle (she tells me I am too eager!) and she wangled 6 split rims and tyres in the purchase price. She amazes me sometimes. We are going away over the June weekend as a shake down run prior to the Canning latter in the year. It's good to hear from someone who runs the tyres and is happy with them. The splits look a little bigger in diameter than the alloys that are on now. I was hoping this would increase the gearing a little. The 75 Series gearing is good in fourth but 1st is very low (top speed 16kph if I remember correctly.)

FollowupID: 432824

Reply By: The Rambler( W.A.) - Monday, Jun 05, 2006 at 12:32

Monday, Jun 05, 2006 at 12:32
Don't let anyone put you off the split rims for 78 series as I have been using them for many years on all sorts of terrain with no problems at all.Ithink you will find that on the sand generally you won't need to go below 18psi and 50 on the bitumen is fine.On the gravel I would not reccomend going below 40psi when loaded.I USE 235/85 Hancooks and can reccomend them highly.Make sure you use quallity tubes and you won't have any problems.Also practice at home changing tyres on the splits as it is quite easy with only 2 quallity tyre levers--if need be you can use a jack to break the bead.
AnswerID: 176796

Follow Up By: Steve63 - Monday, Jun 05, 2006 at 15:14

Monday, Jun 05, 2006 at 15:14
Hi Rambler,
Thanks for the info. I can see that the pressures are generally higher. I have good tyre levers so that part is covered. I'll keep in mind the Hancooks. I tend to change ours over when we do a big trip unless they are quiet new. The only time I didn't we pulled into the Pink roadhouse at Oonadatta with both rear tyres going down! Lesson learnt.

FollowupID: 432864

Reply By: stevesub - Monday, Jun 05, 2006 at 13:28

Monday, Jun 05, 2006 at 13:28
We run splits on our 78 series pop-top camper Front tyres are around 40psi and rears 55psi (Manufacter recommends from memory 30 front, 60 rear). On gravel we have dropped the rears to the same as the front. On the beach, we run standard pressure and have no problems to date but have not done any desert sand driving.

We get 11km/100L at around 90 to 100kph.

Our tyres are old Desert Duellers and we have had 3 blow outs in the last 20,000km, all on the hard stuff. The last one was definetly the tyre as there were vibrations for 10km or so before it blew. They were bad enough for me to stop and check the tyres but as I was on crutches and not supposed to be driving at the time, I did not do a thorough check like I should have. The blow tyres were all around 2/3's worn. The other 2 could have been tyres or tubes but all the tyres totally destroyed themselves.

I am off to get 2 x new Goodyear ATR's tomorrow still 7.50-16 size. Then later in the year will get 2 more for the front unless I get 5 normal rims before then that I am negoitiating on right now in which case it will be tubeless for me - but still AT type skinny tyres as I think they are best for us offroad - we do some club stuff - not too hard, the missus gets too upset if we damage the truck.

AnswerID: 176809

Follow Up By: Geoff (Newcastle, NSW) - Monday, Jun 05, 2006 at 14:26

Monday, Jun 05, 2006 at 14:26
"We get 11km/100L at around 90 to 100kph"

I think you mean we use 11ltr/100km, using 100L for every 11km doesn't sound good to me!!

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FollowupID: 432854

Reply By: Member - Hughesy (SA) - Monday, Jun 05, 2006 at 14:09

Monday, Jun 05, 2006 at 14:09
Steve, I've been using 750x16 and just recently 235/85 on splitties for over 10 years now and haven't had many problems. Most have been from cheap tubes as others have already stated or from having rust and sand in the tyre carcuss during assembly which rubs through the tubes. Don't listen to the general talk on here about dropping pressures to 25psi for dirt etc. That suits the wider wheels well but don't suit the tall skinnies. I've only ever gone as low as 28psi in soft sand and have never needed to go lower. At lower pressures especialy if doing med to high speed the sidewall flex will over heat the tyre very quickly. At a slow pace you could go lower if the terrain demands it.

Highway pressures I would run 40 if unladen and 50 with a load on board. Some 14ply Michelins I had could be run at 100psi and the current Bridgestones I have just put on are 10ply and have a max pressure of 80psi.

Another trick I have started doing is putting silicon in the gap of the split rim to prevent water and sand ingress behind the tyre. Its the only way that I could see how moisture and sand could get in.

In summary - good quality tubes and cleanliness during fitting and you shouldn't have any dramas.
AnswerID: 176816

Follow Up By: Steve63 - Monday, Jun 05, 2006 at 14:52

Monday, Jun 05, 2006 at 14:52
Hi Hughesy,
What pressues do you run on dirt/gravel roads? Same as highway pressure? I see that several replies talk about tube quality. I have a few spares that are Dunlop. Is there any prefered manufacturer? Sorry about the questions, but while I have done plenty of 4 wheel driving I have never had splits before and would prefer to find out things before going bush.

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Follow Up By: Member - Hughesy (SA) - Monday, Jun 05, 2006 at 21:41

Monday, Jun 05, 2006 at 21:41
If I was going to be doing hundreds of km's on high speed (90kmh) dirt and was loaded up I'd typically go down to about 35psi. As I've stated any lower and the side effects of tyre heat build up, outway any possible advantage of puncture resistance.

As for tubes stay away from the korean made / no name brand tubes. Only get quality name brands such as michelin or dunlop etc. When I removed the old tyres and tubes from my 100 series (which I've only just recently bought) I found that all of the tubes were cheapies and you could see where the rust flakes had rubbed numerous indents (as close to holes as you could get) into the tubes in one area of the tube. This being the bottom during fitting, where all the cr&p had settled.

I carry a tube repair kit which I bought off e-bay for about $30. It takes 5 minutes to fix a tube once the hole is found. And there is plenty of patches in the kit. Practice before you go.

If you start the trip with new quality tubes and clean fitting then you shouldn't have any more dramas than someone running tubeless.

Also until about 9 months ago I used to use a jack or the vehicle to break the bead on a tyre. Believe me - invest $175 and buy a beadbreaker. It is tonnes easy and more efficient and I'm kicking myself for not buying one years ago. Good luck.
FollowupID: 432947

Reply By: Geoff (Newcastle, NSW) - Monday, Jun 05, 2006 at 14:32

Monday, Jun 05, 2006 at 14:32
Hello Steve,
What Rambler, stevesub and Hughsy have said is all 100% good stuff on 750x16's.
I've owned 5 Landcruisers and all of them have or had split rims. Apart from a short period on 15" Sunraysia's about 18 years ago I've used nothing else.
Keep them clean on the inside when doing tyre changes and they should be great. like the lads said, practice removing the tyre at home and all is easy after that.
When re-inflating them from tyre removal I always use a clip on air chuck and inflate with the split rim hoop facing the ground. I've never had one seperate and often wonder whether this is urban myth or fact. I'm not prepared to push my luck and find out.
My 78 Series uses about 11ltrs per 100km on 750x16's. Factory TD.

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AnswerID: 176820

Follow Up By: Steve63 - Monday, Jun 05, 2006 at 15:03

Monday, Jun 05, 2006 at 15:03
Hi Geoff,
I was wondering about the hoop flying off on reinflation. I thought it was perhaps a tall story but then I saw a WA government site talking about it. At that point I thought it was probably not a good area for experimentation. I was thinking of putting two ratchet straps around the tyre but putting it face down would be easier. The pressures involved would be huge and I would not want to be in the way of the hoop if it was going somewhere. It looks like I'm in for a bit of a learning experience. It has to be easier than changing the tyre on a steel rim. I did this with with an 11 ply and it just abou killed me.

FollowupID: 432861

Follow Up By: Member - TPM (SA) - Monday, Jun 05, 2006 at 19:35

Monday, Jun 05, 2006 at 19:35
Steve, Geoff,

Beleive it, it is no urban myth. When I worked in Moomba we ran split rims on all our 75s, we always inflated them in the cage on face down with a hose extension. We had photos on our safety board of a guys lower leg hanging off from the ring parting.
He had his leg resting on the tyre during inflation. The dangerous thing with pressure is not how high the number is its the volume/area envolved. 1 psi can kill with a large enough volume.

It is usually old rims it happens too but dont take the chance.

We used to only drive on 32 psi and never had many problems except in summer with the extreme heat( 45 plus ) on Hankooks.

Cheers TPM
FollowupID: 432913

Follow Up By: 12HT75 - Monday, Jun 05, 2006 at 22:27

Monday, Jun 05, 2006 at 22:27
Just make sure that both parts are clean and especially that they are free of rust scale, and I find that it is best to put a lubricant on the tyre beads so that they seat correctly at a lower pressure.
Also just put a few psi in the tyre first, then tap firmly around the split rim portion with a 2lb hammer (keeping the split ring facing away from you) to help it seat in its groove.
I have never had any problems using this method.

FollowupID: 432955

Reply By: Steve - Monday, Jun 05, 2006 at 20:51

Monday, Jun 05, 2006 at 20:51
Tubes: well best ones are .. MICHELIN..with short valves..make sure the insides of the tyres have any stickers removed...and are spotlessly clean..
AnswerID: 176920

Follow Up By: Steve63 - Tuesday, Jun 06, 2006 at 11:06

Tuesday, Jun 06, 2006 at 11:06
Thanks Steve. I have Dunlop spares at present but will remember this for the next set.

FollowupID: 433002

Reply By: Steve63 - Tuesday, Jun 06, 2006 at 11:03

Tuesday, Jun 06, 2006 at 11:03
Thanks everyone for your answers.

AnswerID: 176985

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