TYRES or TIRES, depends on you country.

[moggy1968]

I've always been led to believe that airing down doesn't alter the width of a tyre (well very little) it's the length of the footprint that changes and gives extra grip.

View attachment 141687

That’s exactly right. Airing down can double the length of the footprint, depending on the tyre. Now consider my 235/85x16 tyres, to achieve the same with wide tyres not aired down you would need to be running a width of 470mm!! Also wide tyres build a wider ridge of material in front of them so increasing your rolling resistance

 

[moggy1968]

Standard tyres are likely chosen simply so they can lie about fuel consumption , but bare in mind they have to estimate what kind of driving you do .

Smaller tyres will give better mpg around town because its all stopping and starting , a pushbike with little wheels is much easier to peddle up hill than one with big wheels .

But if your doing long distance at high speed bigger tyres carry you further for less effort so better mpg .

The fat v narrow tyres debate for me is a no brainer , in all but very specific situations the narrow win hands down which is why the worlds military run skinny tyres , they just look rubbish .

I cant find tyres fat enough for my liking but i don't give a damn about fuel consumption and never have my fat tyres failed me where skinny tyres might not have .

This here is a handy website if your considering alternative tyre sizes http://www.kouki.co.uk/utilities/visual-tyre-size-calculator

Don’t really agree with any of that because at the manaufacturing stage, as stated above, all that is about gearing. It has no relevance at that point to fuel consumption and anyway, I don’t think Toyota was ever bothered about that on my 60!! Also it has no relevance to fat vs thin tyres that I was talking about.

 

[clivehorridge]

I've always been led to believe that airing down doesn't alter the width of a tyre (well very little) it's the length of the footprint that changes and gives extra grip.

View attachment 141687

OK, I will read more moggy but I’ve already read a lot. I’m always ready to learn, but I’d prefer to learn why - rather than just take someone’s word for it, simply because I’m more stupid than others because I’ve taken the trouble to ask and question why the obvious is wrong.

Chas’ diagram makes 100% sense, and theres no rocket science in that scenario. It’s impossible to make a tread wider by airing down unless you run flat to bring the side walls down to the ground, and then you’d probably be lifting the Centre of the tread anyway and defeating the object.

But, and here’s the big but that makes me ask the question...

From left to right, 50 psi down to 15 psi, let’s presume a footprint area (length) increase of 80%.

If we also presume that the tread footprint in the diagram is from a 235mm wide tyre, just to put some numbers to it, then replace that footprint with a 305mm wide tyre, you’d gain 30% more footprint in the first 50 psi step, before you start.

Then you’d also gain the same 80% by airing the 305 mm tyre down from 50 psi to 15 psi assuming that the diameters of the tyres are the same.

Now that’s not rocket science either, so I’ve obviously missed some magical bit of math or maybe some hidden physics that’s printed in the only article that I haven’t read on the subject, because nowhere and I mean nowhere in the dozen or so articles I have read have ever answered the above question.

I do understand that penetrating mud can or may somehow increase grip, and I’m ready to accept it, but I’m buggered if anyone has explained why it might be the case.

There’s more suction when you sink which is detrimental and there’s more of a ridge for the tyre to try to “climb” out of which is also detrimental.

So, accepting I’m stupid because my mathematics contradicts the skinny is better, please someone give me an answer that makes sense.

Maybe it’s about weight per square cm, because a bigger footprint will reduce ground pressure, that’s physics, and that will suggest that a mud type tread won’t be getting a full bite into the surface.

Maybe this is the answer, but in a 3.3 tone truck, 4 footprints on 305mm tyres compared with 4 footprints on 235mm tyres, isn’t going to be so catastrophically different to cause total loss of grip.

Answers on a postcard please, I’m really at a loss on this one.

 

[Shayne]

Don’t really agree with any of that because at the manaufacturing stage, as stated above, all that is about gearing. It has no relevance at that point to fuel consumption and anyway, I don’t think Toyota was ever bothered about that on my 60!! Also it has no relevance to fat vs thin tyres that I was talking about.

That's cool Moggy we all have different ways of thinking and i'm just offering mine based on Mike's want to reduce running costs . With that in mind i'd recommend slightly narrower than standard size to reduce rolling resistance and slightly taller than standard size because it might actually make the speedo accurate , how much taller and narrower depends on what's available .

And just to upset you Clive i will ask what kind of mud

nah i reckon you hit the nail on the head with weight distribution , you have a vid somewhere when a track down by the river was blocked and just for fun you went over it and back again with me doing a bit of spotting for you . There was maybe 30ft of flat wet slop on the entry/exit to the obstacle and you had all 4 wheels spinning as you crawled through it , while you paddled over it i think skinny tyres would have dug into it giving you more grip .

 

[Gary820]

All I know @clivehorridge on the 255/85 my 80 isn't at its best. Yeah it's a bit better on fuel and pulls away a bit better.
It's not great in mud (only time I've been properly stuck) not great on rocks and breaks traction on wet tarmac easily.
Easier to drive on bumpy country lanes though.

Now on the 35x12.50 I've driven in worse muddy conditions without issues, rocks aren't an issue and not as bad on wet tarmac (the coopers are better then the bfgs in this respect) handles snow nicely even in rwd.

Does 'tramline' more but so does my Beemer on its wider 18's. (Drives in snow on the smaller 16's though)

Yes not the same tread pattern but still a massive difference.
Does run on the wrong fuel though so maybe part of the formula

 

[clivehorridge]

That's cool Moggy we all have different ways of thinking and i'm just offering mine based on Mike's want to reduce running costs . With that in mind i'd recommend slightly narrower than standard size to reduce rolling resistance and slightly taller than standard size because it might actually make the speedo accurate , how much taller and narrower depends on what's available .

And just to upset you Clive i will ask what kind of mud

nah i reckon you hit the nail on the head with weight distribution , you have a vid somewhere when a track down by the river was blocked and just for fun you went over it and back again with me doing a bit of spotting for you . There was maybe 30ft of flat wet slop on the entry/exit to the obstacle and you had all 4 wheels spinning as you crawled through it , while you paddled over it i think skinny tyres would have dug into it giving you more grip .

The wrong sort of mud, obviously Shayne, if i was driving

Yes, I’d forgotten about that episode by the river. I was a bit ashamed of keeping them spinning like that, but I was more interested in keeping the momentum going, and it did work, admittedly.

It was gloopy on the surface wasn’t it? I’d have been in trouble if it had broken through and sunk, for sure. There was a bit of a cross fall as well IIRC, I remember having a bit of steer set to stay straight.

Sorry Mike we’ve gone of topic, so thanks to Shayne we can get back on track maybe.

 

[clivehorridge]

All I know @clivehorridge on the 255/85 my 80 isn't at its best. Yeah it's a bit better on fuel and pulls away a bit better.
It's not great in mud (only time I've been properly stuck) not great on rocks and breaks traction on wet tarmac easily.
Easier to drive on bumpy country lanes though.

Now on the 35x12.50 I've driven in worse muddy conditions without issues, rocks aren't an issue and not as bad on wet tarmac (the coopers are better then the bfgs in this respect) handles snow nicely even in rwd.

Does 'tramline' more but so does my Beemer on its wider 18's. (Drives in snow on the smaller 16's though)

Yes not the same tread pattern but still a massive difference.
Does run on the wrong fuel though so maybe part of the formula

I hated my skinnies Gary, when I had them, but maybe I should have persevered more.

Tramlining, well yes, tell me about them, we’ve got miles of them here in the city and when it’s wet, they’re a nightmare. They shred tyres as well, because they’re generally worn to exhaustion and the anti splash strips (alongside the rails) get worn thin and buckle up, like bloody knife blades.

 

[mike smith]

Ok guys thanks for all your responses, Animal Mother gave me what i was looking for. I did not word this post very well, my mistake. What i was looking for was advice on the width of the tyres, not getting bigger tyres so it was my fault for the bad wording.

Whats happened to Sheffield, my family came from there and were bombed out during the war, am i allowed to mention the war lol. What got me started on this thing was that the current tyres on LC look like balloons and feel like that, i wanted to know, and i worded it badly because i wasnt sure, its the width of the tyres on my 105. I see guys with 80/100 series driving round with much narrower tyres than i have on mine. The 50th anniversary model has what i have been told, are deep dish wheels and that explains, in my mind, that i need to to a narrow tyre for better handling, am i wrong in this assumption.

 

[moggy1968]

Ok guys thanks for all your responses, Animal Mother gave me what i was looking for. I did not word this post very well, my mistake. What i was looking for was advice on the width of the tyres, not getting bigger tyres so it was my fault for the bad wording.

Whats happened to Sheffield, my family came from there and were bombed out during the war, am i allowed to mention the war lol. What got me started on this thing was that the current tyres on LC look like balloons and feel like that, i wanted to know, and i worded it badly because i wasnt sure, its the width of the tyres on my 105. I see guys with 80/100 series driving round with much narrower tyres than i have on mine. The 50th anniversary model has what i have been told, are deep dish wheels and that explains, in my mind, that i need to to a narrow tyre for better handling, am i wrong in this assumption.

I think most people understood it was about width and we've gone into the ins and outs above

 

[mike smith]

Ok guys , once again i have done it, i failed to mention that the chances of me going off road, unless you count typical Australian dirt roads, is like me winning the lottery, I got the cruiser for the towing, the 7 seats and because i have 5 grandkids to run around. So thanks for all your help, but i am getting too old for off roading, i used to do loads in my younger days, if i want to go off road now, i choose a picnic ground near a river. What i am trying to get, and i have mentioned it before, is just slightly better mileage, that i can justify to er indors, to keep the LC and not change it.

 

[moggy1968]

Ok guys , once again i have done it, i failed to mention that the chances of me going off road, unless you count typical Australian dirt roads, is like me winning the lottery, I got the cruiser for the towing, the 7 seats and because i have 5 grandkids to run around. So thanks for all your help, but i am getting too old for off roading, i used to do loads in my younger days, if i want to go off road now, i choose a picnic ground near a river. What i am trying to get, and i have mentioned it before, is just slightly better mileage, that i can justify to er indors, to keep the LC and not change it.

well yes, that does change things a bit!!!

 

[Towpack]

Ok guys , once again i have done it, i failed to mention that the chances of me going off road, unless you count typical Australian dirt roads, is like me winning the lottery, I got the cruiser for the towing, the 7 seats and because i have 5 grandkids to run around. So thanks for all your help, but i am getting too old for off roading, i used to do loads in my younger days, if i want to go off road now, i choose a picnic ground near a river. What i am trying to get, and i have mentioned it before, is just slightly better mileage, that i can justify to er indors, to keep the LC and not change it.

If this is all you’re really after Mike then, personally, I wouldn’t be too concerned about the width, more the tread pattern. Steer clear (no pun intended!) of AT pattern or anything remotely connected with off road driving and go for a 100% road biased tyre designed for on road grip and economy. Such a tyre will still give you enough grip for the ‘picnic’ situations you mention. You could also go with a narrower tyre if you wish but the economy gains will be minimal IMO compared to those gained by choosing a road tyre over an off-road or dual purpose tyre. The wear rate may also be higher.

 

[mike smith]

If this is all you’re really after Mike then, personally, I wouldn’t be too concerned about the width, more the tread pattern. Steer clear (no pun intended!) of AT pattern or anything remotely connected with off road driving and go for a 100% road biased tyre designed for on road grip and economy. Such a tyre will still give you enough grip for the ‘picnic’ situations you mention. You could also go with a narrower tyre if you wish but the economy gains will be minimal IMO compared to those gained by choosing a road tyre over an off-road or dual purpose tyre. The wear rate may also be higher.

Thanks for that, so an ordinary tyre will be fine.