245/75 - 17 anyone?

[HIKDJ Lurker Find all posts View Profile Close HIKDJ]

Has anyone fitted LT245/75 - 17" ?
I believe they would look better on the 7,5" wide rims, which are a bit narrow with the 265/70 tires. The diameter would be nearly identical. Also the load capacity is exactly the same (121), at least for BFG AT's.

There is a theory that narrower tyres perform better on soft surfaces such as sand. Looking at Paris-Dakar vehicles, you never see ultrawide tyres. Can anyone confirm or contradict this from personal experience?

[fishnut Advanced Member Find all posts View Profile Close fishnut]

Just based on what I know - biology - wider seems to be the go for sand. Animals that run on soft sand tend to have evolved feet with wider footprints - eg camels. Other smaller beasties that don't weigh as much still have adaptations to spread the load - ie - some small mice and lizards have webbed or hairy feet to create more surface area. Ever seen a sheep try to run along a beach? It's not overly efficient.

4wd teachers will tell you that it is the length (not width) of the footprint on tyres that give you the advantage in sand. This is because the sides of the tyres don't bulge much when you deflate- rather, you lengthen the footprint.

but I'm sure a combination of both would be the best scenario. As an example, I had a friend who made a hand-trolley to get his dinghy onto the beach. He went with the bigger rolling diameter theory and put road-bicycle tyres on and it just sunk all the time. He then put wheelbarrow tyres on and it worked much better. He eventually ended up with wide motorcycle tyres and they were the best. Wider and longer footprint won!

So after all that - I can't see how 245 could be better than 265. Happy to be corrected

my friend call his 245s 'Pizza Cutters' :lol:

[MTpockets Advanced Member Find all posts View Profile Close MTpockets]

My old beach buggy had balloon tyres on the drive (rear) and piza cutters on the front. it worked a treat as the rear tyres were only ever 4-6 psi, and the front about 10psi. The front with no weight, (volkswagen) floated, and the rear footprint was huge. There was no dunes the old girl could not drive, and never looked like bogging.
motto of the above.... skinny if no weigt, fat for the weight. and that was a 2 wheel drive open diff buggy.

However skinnys are brilliant on rocks at slow speed.

[fishnut Advanced Member Find all posts View Profile Close fishnut]

Interesting Les. After you last comment, I realised I missed a couple of words above that should be included. see below

So after all that - I can't see how 245 could be better than 265 on sand.

[MTpockets Advanced Member Find all posts View Profile Close MTpockets]

With the stock size tyres on all my 4'bies were brilliant on sand, due to only ever owned auto's. My Surf had fairly skinny 15" but drop the pressure and with the auto was great on sand. The Prado with 265 D694's is also brilliant with the auto. I think momentum is always the key in sand.

Fishnut..... what was interesting with my buggy, the rear tyres were old aircraft landing tyres, and were bloody strong, and 6psi worked a treat.

[leachy_9 Advanced Member Find all posts View Profile Close leachy_9]

I'm with Fishnut, given the same overall diameter, and assuming the same tread pattern, the wider tyre would give better performance in the sand. When you start altering both overall diameter (length of foot print) and width the comparison become a whole lot more complicated.

Leachy

[HIKDJ Lurker Find all posts View Profile Close HIKDJ]

Thanks you all for your input. I will take your advice into account and go for the wider tyres.

[Hutch Addicted PP Member Find all posts View Profile Close Hutch]

Could you post the photo's please Matt.

[Hutch Addicted PP Member Find all posts View Profile Close Hutch]

I remember talking to the MT rep about these and as he pointed out the square edged mudder in a 245 width is much difference to a standard dunlop 265 series because of the rolled edge tread of the road going tyre is not really 265mm wide.