Tyre sizes

The tyre's profile (65, 70, 75 etc) refers to height of the sidewall as a % of the width.

So a 265/70 has a sidewall height of 185.5 while a 265/75 has a sidewall height of 198.75. All things being equal (brand, model, inflation, etc) the total extra diameter between the two tyres is 26.5 mm.

Have a look in the archives, and also here Overlander forumSmile, you're on ExplorOz
Rohan (Sydney - on the QLD side of the Harbour Bridge)

Crowe, this is correct provided all other things (brand, model, inflation etc) are equal. In the great search for information to support my choice of tyre, without requiring an engineer's cert, I have discovered that there are vastly different "rolling" circumferences between makes and models of tyres in the same size. So, mixing and matching different brands and models as well as sizes, could result in a significant difference, in rolling circumference, for the purpose of interchaneability.

A 4% difference in RC based purely on the diff between a 70 and 75 profile of the same tyre probably wouldn't cause too many problems as long as there was sufficient wheel slip to equalise the wheel revolutions. Using a diff-lock would change this equation somewhat.Smile, you're on ExplorOz
Rohan (Sydney - on the QLD side of the Harbour Bridge)

the problem with this theory is simple.tyres of a different diameter on the same axle will cause accelerated wear on the outside edge of the smaller diameter tyre, as well as place strain on the diff centre.
(think about it...) :)
running them on dirt for a short period would be ok, but go near bitumen and things will wear very quickly. thats why we rotate our tyres every 5k, so that every one of them wears down evenly.
as the saying goes in the world of tyres,,,,don't mix and match...
sell the ones off the camper ort 4by and get ones that match the tyres you keep..

rick.

need to multiple 13mm by 2 for both sides of the tire so in essence it will be approx 26mm lift, 13mm on one side wall and another 13mm on the opposite side wall

Lift WILL be 13 mm (ground to axle, 185mm vs 198mm sidewall height + half the 16 " rim), other 13 mm will be "guard filler", therefore overall 26 mm larger diameter tyre.

I nearly made the same boo boo crowe. But of course any additional height is only gained from the radius below the centre."Live today as if there may be no tomorrow"

Wombat

Wombat,

Yes, Cooper sell the AT in 265/75/16LT size. I have these on my Patrol and they are great, good grip for the off-roading I do, excellent in sand and also quiet on road.

The following link will let you make up your own mind and specific pages show all the dimensions you ever wanted to know about tyres, certainly enough to answer all your questions.

www.coopertires.com.au

Regards,
Hugh

15% of standard you can go without causing problems.

if in doubt Vicroads site has ALL the info on there, if u can find it.

I'll think twice about calling someone a legend again! I wonder if Dr Harry's a legend? I spoke with Coromal with regard to getting Coopers on the camper on delivery but they say no go - she only comes with Bridgestone ATs. So if I can ask one more question; Should I put the legal 265/70/16s on the Triton and then replace the original Bridgestones on the trailer with the same tyres to get a match and if I did this do I trade the three brand new Bridgestones in or sell them privately?

Thanks for the help.

PS I wonder if any Vicroads inspectors would which tyres are larger than legal?"Live today as if there may be no tomorrow"

Wombat

gday wombat.
my chooice would be just keep the 265/70/16 on your triton.
if you want to change the tyres on your camper just so you have extra spares i would sell them privately.
i run 31" on my patrol and 30"on the camper and have one spare for the patrol and one spare for the camper.
if worst came to worst i9 would just fit the 30" to the front of the patrol if i needed to.

ps most peoplpe at vic roads wouldnt have a clue about tyre sizes but they have a group of coppers who have been trained to know the roadworthy laws(there was 10 there when i did my course).
and of course your insurance company.got over no fraser.
get on with life(more weekend fun)

Thanks for the great advice which I shall take. What should I pay for five Cooper 265/70/16 ATs and is your new place of employment a Cooper agent?"Live today as if there may be no tomorrow"

Wombat

Hit me offl forum if you prefer;
Paul
at
backhouse-thomas
dot
com
dot
au"Live today as if there may be no tomorrow"

Wombat

gday wombat.
you should be paying about $245-250each for your tyres.
that seems about the average price.
just remember to screw the tyre place for free rotatio/balance.
might be the only thing that decides where you buy them.got over no fraser.
get on with life(more weekend fun)

Yeah the poor old Triton would look like a limping wombat. Hey I thought you guys would have been off by now enjoying the peace and quiet. When do yo leave? "Live today as if there may be no tomorrow"

Wombat