Opinions: Mud Tyres-height v's width

[shortSteve]

Hey all, been hearing some mixed comments re: mud tyre sizes and what is best?
Scenario is I have a spare set of genuine MN alloys (16x7) to use as play tyres. I currently run D697's in 265/75/16, love the tyre but starting to venture into boggier areas, both soft soil mud and clay based, so looking at a spare set of "play tyres" in the form of a reasonable muddy. For the purpose of this exercise, will use the Bridgestone 674...

Current tyre is a 804mm diameter, same size in muddy (265/75/16) is 810mm, so a little taller, guessing in tread block height. Other option is a 235/85/16, obviously a little narrower but taller at 818mm diameter. Neither should scrub based on current clearance.

So, my thoughts are that, on a firm based mud, you would be better with a narrower tyre to break through the gloop to the firmer bottom, having a greater weight per footprint, and the slightly taller height would be a little benefit too.
But also hearing that on sloppy soil based mud, where there is no firmer bottom, a tyre with greater surface area will give more floatation, relying on the greater tread contact patch to drive through.

So, which is more correct? Or is it really a case of each size would be better in a different scenario?

For comparison purposes, both tyres have the same load/construction as current tyres, and would be run at similar pressures.

Thoughts and advice please?

sS

[biggibbo]

The wider tyre will be more of an all rounder and the extra width can help keep the vehicle off walls in ruts.

The extra 8mm only ends up being 4mm in height, and when deflated would be almost a negligible difference.

The extra width would also help on rocky climbs, steps etc as you will have a bigger contact patch.

Tbh I've never really been sold on the idea of cutting thru the slop.

I would be going wider, but keep in mind it will affect economy, and gearing

[L200Shogun]

Back when I was a boy 4wd tyres where all 7.00 R 16 (ie 175mm wide) and they quite happily went every where.

Some places on the net say skinny and tall is better.
http://www.outbackcrossing.com.au/FourW ... yres.shtml

[shortSteve]

The wider tyre will be more of an all rounder and the extra width can help keep the vehicle off walls in ruts.

The extra 8mm only ends up being 4mm in height, and when deflated would be almost a negligible difference.

The extra width would also help on rocky climbs, steps etc as you will have a bigger contact patch.

Tbh I've never really been sold on the idea of cutting thru the slop.

I would be going wider, but keep in mind it will affect economy, and gearing

Yeah, I know the gearing thing well...but having gone from a 750mm od to 804, and extra 6 or 14mm ain't gonna be a deal breaker. To go to a 285/75, with a 838mm od, is gonna be a struggle with the weight I carry, hence sticking closer to around 32".

[furious]

tyre grip is based on the ration of the length and width of the contact patch. You want to look for the biggest ration of length and width.

[Cowboy Dave]

One issue with the skinny and tall tyres is you have more sidewall which can flex. Maybe on your figures it's not much but I've watched a triton shift sideways and almost into a tree purely because it had tall tyres and at low pressures they just weren't stiff enough to hold their shape when the truck tilted a bit sideways.

[biggibbo]

That was hilarious that day. Wonder if he will chime in?

[shortSteve]

One issue with the skinny and tall tyres is you have more sidewall which can flex. Maybe on your figures it's not much but I've watched a triton shift sideways and almost into a tree purely because it had tall tyres and at low pressures they just weren't stiff enough to hold their shape when the truck tilted a bit sideways.

This interests me, and from watching others with 33's v's 32's, I would have agreed at first. But then noted the load rating/ply count, and the guys running big soft muddies usually only had a 112ish load rating, compared to 120+ on the 32's. Softer sidewalls=more flex. Better deformation for traction, more susceptible to sidewall damage and that sliding feeling. Of note was the sidewall heights of both these options and my current tyres vary by only 5mm, so not expecting much difference.

Will the narrower tyre be better suited to the 7' rim by not "bagging" out as much as the 265 does?

[mIwoo]

Biggibbo- see I'm the opposite. Ive never been sold on the wide tyre philosophy. The taller, skinnier tyre principle is what I think too. The problem is the yanks like their big wide tyres and market their tyres that way. So wider tyres have become the standard (i.e. 285/75R16 vs old school 235/85R16). Plus, on road, with smaller tyre walls, slightly wider tyres (i.e. 265/65R17) provide on road steering benefit, not off road benefit. As such the 265's, 285's, 305's etc have become the 'norm' .... IMO anyway....

[mIwoo]

To the OP- TBH- considering tyre cost, availability and functional ability... just stick to the LT265/75R16- well thats what I would do anyway.

[mIwoo]

oh... do yourself a favour- either choose the bighorn or the dynapro MT as your muddy- you won't regret it!

[al coholic]

While your fairly well spot on with your summary Steve, the difference in width between the wide and skinny tyres that you refer to is what...30mm?? It's not really here nor there is it

The Triton Dave refers too above was running 34" tyres....so a fair bit different to either a 235 or 265 tyre (32's)

I can't see there being much benefit or difference either way you go.

I'd be looking more at tread pattern than the few mm gain or loss in tyre height or width

Also, a 265 tyre is arguably more readily available compared to a 235 if you ever needed one quickly....

[al coholic]

Biggibbo- see I'm the opposite. Ive never been sold on the wide tyre philosophy. The taller, skinnier tyre principle is what I think too. The problem is the yanks like their big wide tyres and market their tyres that way. So wider tyres have become the standard (i.e. 285/75R16 vs old school 235/85R16). Plus, on road, with smaller tyre walls, slightly wider tyres (i.e. 265/65R17) provide on road steering benefit, not off road benefit. As such the 265's, 285's, 305's etc have become the 'norm' .... IMO anyway....

Not saying you're wrong but in every aspect of motor sport and racing, they go a wider tyre to increase the tyre contact with the track, therefore increasing grip
4wding is also all about grip, so to me the same theory applies, wider tyre equals more grip.

Why do we all air down before hitting low range tracks? To increase the tyre contact with the ground...whether it be dirt, ruts, rocks or mud. Tyre grip is king

That's where I don't completely understand the skinny tyre theory, you'll always have less tyre in contact with the ground.

Unless the only type of 4wding you do is driving thick bog holes, I can't see the skinny tyre winning

However, again, comparing a 265 and 235 tyre is negligible. Comparing a 12" tyre to a 7" tyre would be a different argument

[4wd26]

all right all right

tyre whore chiming in

the tyres that the guys seen squirm were as you surmise 112 load rating simex centipedes, these were 245/85/16 but they are 855mm diameter

I have also run 236/85/16 tyres in a goodyear MTR Kevlar out into the desert (big red and some of the fast dirt out that way, Bourke development road and also the glasshouse mountains wet clay) these are a high load rating and don't flex any where near the same as the simex.

everyday tyres I run are goodyear MTR 265/70/17 great all round tyre

I have also run 265/75/16 tyres in all terrain



so in summary, if you are set on a all terrain type tyre I would get a 265 series, it is never going to bite deep into any surface as it is not a muddy so the advantages in that terrain don't apply, if on fast dirt then maybe the 235 only due to being able (as a all terrain) cutting through the slippery gravel into the clay base


go the 265 only because you also recommend the all terrain type tyre.


more information and I can give more examples- check out my trip reports in my signature for a bit of a rolling report on different tyres/ sizes and types in different terrains.

[4wd26]

http://www.beadelltours.com.au/tyre_footprint.html

might pay to take a look here to see that skinny tyres actually give more flotation (length of footprint) rather than wide tyres.


same rule of thumb applies when operation excavators and dozers (read swamp dozers) weighing over 40 tonne yet have a lower PSI footprint than a 4x4

but even they get it wrong occasionally

[shortSteve]

oh... do yourself a favour- either choose the bighorn or the dynapro MT as your muddy- you won't regret it!

Cheers, although on our last run out to the Holland Track and Woodlines, only 1 truck suffered punctures, bighorn. It was well driven, well set up (a lot lighter than my Triton) but suffered sidewall punctures, no one else did, even one guy with std oem at's came off puncture free. Traction was another story tho, and all the at's struggled on Woodlines, various brands of muddy did it easy.

[motoz]

It's a pity that 255/85 x 16 is considered such an odd size in Australia and therefore over priced.

[TUF909]

Believe it or now an M1 Abrams tanks has a lower pound per square inch that the old 110's!

[Homer]

I'm a skinny tyre guy when it comes to both mud and sand..the right tread for each...MT's are shit on sand no matter what anyone tries to tell you

Tyre pressure pretty much only increases the length of footprint, not looking for width.

I have wider tyres because I'm a bit of a tool and like the look and have the factory LSD and an auto (and V6) so it goes pretty much anywhere in the sand anyway

Have a look at what the Rangers on the beach use mud is similar...but different.

[shortSteve]

Cheers all, will look into it a bit more in the new year. Cost was surprising, the 674 muddy in 265/75/16 retailed at ~$280, the same as the 697AT in that size. The 235/85 was ~$240, from previous experience the less popular tread sizes are normally more expensive, shocked to see around $40 a corner difference!

Looked at some Achillies last night on a Triton, really aggressive and large tread blocks, much more so that the Bridgestone and around the same price as the 235/85. Will check out the Hancook ones too...

[biggibbo]

Just make sure if ya go skinny, that you have the right rims to match. My previous muddies were a set of 245/70/17' and when deflated would pop off the beads all the time. Got to the point I got rid of a brand new set of muddies and went to the 265's

[snowman]

I'm a skinny tyre guy when it comes to both mud and sand..the right tread for each...MT's are shit on sand no matter what anyone tries to tell you

Tyre pressure pretty much only increases the length of footprint, not looking for width.

I have wider tyres because I'm a bit of a tool and like the look and have the factory LSD and an auto (and V6) so it goes pretty much anywhere in the sand anyway

Have a look at what the Rangers on the beach use mud is similar...but different.

i liked this post so much i just had to bump it.

[snowman]

265 / 70 / 17 or 265 / 75 16 in my opinion are the sweet spot of tyres for these cars.

I have a set of 285's for on road and i reckon that is where a wider tyre can shine.

I only run OEM rims but if i was going to go a set of aftermarket for off road i would go with a slightly less positive offset. most people who have reckon stability is increased but the other big benefit is that extra 20mm or so can keep you off the walls of those big ruts.

make sure any aftermarket rim has the right load rating

[Sootie]

I don't have enough experience to comment as I have only had HT's and Dynapro MT's on my truck but the Dyna pro's in 265 75 16 are only about $230 a corner (at least around my way) which puts them around the same price as the skinny ones