Outer Limits 4x4 Board

sidewayz wrote:ofcourse it matters.

when the largest tyre u can run legally is 33" and Mr c0cksmoker traffic branch reads his 33" of the sidewall then u want to get as much of that 33" as u can.

as far is this problem goes, i have decided to run 305/70/16 kuhmo kl71 and 16" rims. the supplier has assured me the will measure the full 840mm that they are surposed to. if they do not, i gues they wil be going back...

matty

Mate thats not true 33s are not legal on QLD roads.. been defected twice now with 33s along with the other rubbish :(

Far out Qld sux.

Yeah mate a lot of rubbish getting around what is and isnt legal you may be lucky to get away with 33s but they are definately not legal and we can only have 2.5inch of suspension (33% more bump stop clearance) and 2 inch body... shocks are not allowed to extend any further than standard, ANY aftermarket panhard is a no go, offset castor bushes are a defect also... been through it all :( hopefully the new rules relax it a bit but by the sounds of it no

F%$^ that, register interstate.

How does $230 a tire sound at bob jane in penrith for 33" M/T Bighorns?

Tom0 wrote:

rick130 wrote:Just fitted 255/85/16 Big Horns and ran the stagger tape around one.
Mounted on a 6.5"rim and at 31psi it measured exactly 2650mm around, which works out to 843.5mm, or damn close to what the book calls out (33.3")

If you do the sums, 255/85/16s should be 839.9 ((255x85%x2)+(16x25.4)) ... so your 843.5 measured via the radius could just be your error in measuring - radius is pretty hard to measure accurately.

On the numbers, 305/70x16 = 833.4 = 32.8"

285/75x16 = 816.8 = 32.16"

But on an 8" rim it will be higher than on a 10" - makes sense because it's squashed together more to fit on the 8".

Huh ? who measured the radius ?
I ran a stagger tape around the tyre OD, the only accurate way to measure a tyre (measured a lot of race tyres years ago)


The sidewall numbers are only an approximation, the tyre companies actually measure production samples and these are what go on tyre spec sheets (or the good companies do)
Maxxis and BFG both state their 255/85's are 846mm/33.3" in diameter, with the BFG being 254mm/10" in section with, and the Maxxis being 262mm/10.3" in section width, which is what it measured up at.

Tyres vary in size after they come out of the mould quite a bit, and particularly batch to batch, but the differences aren't inches, more millimetres.

What's the OD?

846mm on what size rim?

Surely they are taller on an 8" rim than at 10" - they should spread out wider when on a 10" and so logically not be able to be as tall... according to the spacial reasoning computer in my head.