Thread: Narrow tyres V Wide tyres

Originally Posted by LRHybrid100

4WD Monthly did an article ages ago about Wide vs Tall tyres and the the tall skinny ones came out on top - its all down to air pressures.

When air pressures are reduced the "footprint" of the tall skinny increases more proportionally than the wide tyres, as the footprint gets bigger length ways and not width ways - if this makes sense?

LRH

this doesn't make a lot of sense to me but i'm not saying it's wrong, but surely even if the tyre is wider then when you let air out it will still elongate in proportion to the amount of air you let out as will a thinner tyre
why would a thinner tyre elongate more, i would think they would both elongate the same (as long as the rubber was the same i.e 1 not harder than the other) and then the wider 1 would still have a larger footprint due to the fact it's wider.
tho i understand and agree with the statement of a wider tyre having to push more sand away out of it's path

letting the air down on a wide tyre does not make the tread wider just sidewall bulge, however letting a skinny tyre down gives it more length - and therefore a greater proportional footprint.

LRH

Narrow
7.50 x 16

• The SIII did the Simpson East-West with 7.50x16 tyres.

• After the tyres that came with the Defender wore out, I replaced them with 7.50R16.

• The trailer has 7.50x16

• The Range Rover has 215/85R16 (tall & skinny).

Narrow tyres have a long foot print with a narrow face. Wide tyres have a wide face. To use a hyperbole - imagine a tank (long & narrow) and a steam roller (wide) trying to get through any type of terrain. The long narrow footprint will always traverse it better. Plus less stress on steering components etc.

Originally Posted by Michael2

To use a hyperbole - imagine a tank (long & narrow) and a steam roller (wide) trying to get through any type of terrain. The long narrow footprint will always traverse it better.

I must remember that analogy when arguing with the wide tyre brigade. Makes perfect sense.

I use 7.50x16 on both the 110 and the 2a. For a given pressure, and ignoring the stiffness of the sidewalls, the ground contact area will be the same regardless of the tyre width - pressure times area will always equal the weight on the wheel. So it comes down to whether you are better off with the contact area more or less elongated in the direction of travel, and it seems clear that elongation in the direction of travel is preferable, as it will tend to bridge over irregularities rather than to drop into them, and so be less likely to get stuck. Of course, this applies only where you are likely to get stuck anyway. On hard surfaces such as bitumen, the advantage of wider tyres is that the wider effective track improves stability. Against this is higher loading on all steering and hub components, and more bump steer as the leverage of an irregularity hitting the outer or inner edge of the tyre is greater.

Increasing the tyre width over the manufacturer's design also means you are operating outside the design loads, particularly on steering components and wheel bearings, but ultimately on everything to do with the suspension and drive train, from wheel studs to wheel bearings to half axles to transfer cases.

In summary, the only advantage of wider tyres is a small increase in stability on bitumen, as against reduced life on mechanical components, worse steering and turning circle, and generally more prone to damage.

Note that the above applies to wider tyres. As soon as you increase the overall diameter, it is a different story. As far as grip, traction and resistance to getting stuck go, an increase in diameter is all good, and may well outweigh the effects of increased width. But increases in diameter also have drawbacks, from changes to effective gearing to increased leverage of the tyre on driveline and brakes, making breakages much more likely.

John

7.50xR16's

Came with the Defender and never looked back for offroad work.

Believe in the same reasons as stated previously about tyre elongation.

had 10.5x15s on the series when i got it.
went to 7.50x16s for availability 2nd hand

very happy,big difference,all good

Ha I love the fact that a 4wd magazine have claimed a wider tyre does not elongate when aired down.

For mud I will agree generally the skinny tyre will bite down to the hard stuff and get you through where as times big wide treads will just slip along the surface.

BUT in anything else I have found the slightly wider tyres to perform better, when aired down correctly they eleongate plenty.

And my opinion of this is related to the more extreme offroad adventures. For everyday use and general touring I would have no idea