TYRES or TIRES, depends on you country.

mike smith Mar 11, 2018

  1. moggy1968

    moggy1968 Well-Known Member

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    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
     
    Chas likes this.
  2. moggy1968

    moggy1968 Well-Known Member

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    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.
     
  3. clivehorridge

    clivehorridge Well-Known Member Supporter Guru I am in romania

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    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.
     
  4. Shayne

    Shayne Well-Known Member Guru

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    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 :lol:

    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 .
     
  5. Gary820

    Gary820 Well-Known Member I am in great_britain

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    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 :lol:
     
  6. clivehorridge

    clivehorridge Well-Known Member Supporter Guru I am in romania

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

    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.
     
  7. clivehorridge

    clivehorridge Well-Known Member Supporter Guru I am in romania

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    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.
     
    Gary820 likes this.
  8. mike smith

    mike smith Member I am in australia

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    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.
     
  9. moggy1968

    moggy1968 Well-Known Member

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    I think most people understood it was about width and we've gone into the ins and outs above
     
    clivehorridge likes this.
  10. mike smith

    mike smith Member I am in australia

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    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.
     
  11. moggy1968

    moggy1968 Well-Known Member

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    well yes, that does change things a bit!!!
     
    clivehorridge likes this.
  12. Towpack

    Towpack Well-Known Member I am in england

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    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.
     
  13. mike smith

    mike smith Member I am in australia

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