Thread: Quick question re tyre size/RPM - real world experience

For wats its worth i am running 265/75/16 on my d2. BFG long trail. I am not to happy with them as there is a fair bit of side wall flex when run at normal road pressures but when the full lenthgh roof basket is on and approx 250 kgs is on the roof and about 300 kgs inside and pumped up to 50 PSI they seem to come into there own. The long trails are a heavy duty tyre fitted mostly to the F style trucks so will handle high pressures with heaps of kilos on board. I would not recomend this tyre as a daily driver type tyre or as a shopping trolly tyre. But i am stuck with them for probably 4 years as they dont seem to want to ware out even after 20,000 kays not even a scratch and we have done some tough tracks.

On my series 3 i am running retread yokahamas 8.25 by R 16 Snow and mud tryes and they seem to be the goods at 60 bucks a pop ( Why not) as i have taken the truck through some pretty rough stuff and the tyres have held up ok even running pressures as low as 12 psi and as high as 70 psi

But thats mt 2 cents worth.

mate.....if you want some good road rubber for your fender.....
get yourself a set of the original general grabbers they come out with......

plenty of people are getting rid of their original tyres for aftermarket ones.....
and i must say i am impressed with what the grabbers are capable of.....
im on my second set.....i only got 80,000kms out of the first set.....and they were only changed because the second set turned up.......they still had tread on them........


if you look around you will find them at the right price.......

Originally Posted by isuzu110

Whilst we wait for people with _real_ experience to chime in, my 2c worth.

* Not sure of your Vic laws, but in Qld, your vehicle would not be compliant as the diameter of the tyre will have changed by -62mm, more than the permissable -26mm allowed. Even with real world manufacturing differences, that's a big gap from -62 to -26mm

"The rim diameter may be varied from the standard size but the overall diameter of the tyre must not vary by more than +15mm or -26mm."

*Thread hijack altert*

WTF: I'm sure i've said this before, but what is the real truth behind non-standard tyre sizes?

My RRC had RRC standard size 205/75/16 tyres which is actually 28" (i said 29" before). Thats 711.2mm diameter. My 31" are 787.4mm. Thats a difference of 76.2mm. I've seen bigger tyres on Rangies and on other 4x4s: some are 33", 35", 38", need i go on? 38" on a Rangie is 254mm oversize (slightly more than the allowable +15mm!!!!!!)

Are these tyres illegal? Is my Rangie unroadworthy (the tyres, not everything else )? I had a cop car sitting behind me the other day, and i didn't get pulled over! I've been on 4x4 outings where everyone is wearing 35" or bigger and passed the boys in blue! None of these 4x4s are engineered in any way, just big lifts and big rubber.

I realise i am quoting a comment about QLD laws, but it is still the same country and (i believe) planet.

Please help. Apologies for the hijack.

Pete

Ok, I googled your Vic Vehicle Standards available here

Seems they may be technically more restrictive than Qld on tyre modifications as they mention only +/- 15mm change in diameter versus the "largest diameter tyre specificed by the manufacturer" in that link. By all means, check it yourself, and don't take my word for it.

No I don't claim to be an expert on Vic regs and yes, I too saw plenty of large tyred 4WDs in my time living in Vic that didn't seem to attract police attention.

Not trying to be alarmist or a kill joy, just do your own homework and know what risks you are taking.

Enjoy your rubber!

Originally Posted by isuzu110

Pete

Ok, I googled your Vic Vehicle Standards available here

Seems they may be technically more restrictive than Qld on tyre modifications as they mention only +/- 15mm change in diameter versus the "largest diameter tyre specificed by the manufacturer" in that link. By all means, check it yourself, and don't take my word for it.

No I don't claim to be an expert on Vic regs and yes, I too saw plenty of large tyred 4WDs in my time living in Vic that didn't seem to attract police attention.

Not trying to be alarmist or a kill joy, just do your own homework and know what risks you are taking.

Enjoy your rubber!

Maybe i should start an AULRO poll: Are you're big tyres and lift engineered and legal?

I think only those that have had their big tyres engineer approved would respond.

Originally Posted by Slunnie

I think only those that have had their big tyres engineer approved would respond.

Mine aren't

Just because you see vehicles fitted with large tyres does not mean they are legal. There are probably a very large number of vehicles being driven daily that are technically illegal because of various modifications that should have been engineered but haven't, and many of these would not pass engineering scrutiny. Unless the vehicle appears to be outrageous, or the driving of it does, it is very unlikely that the modifications will be queried, and even in the case of an accident, unless it is seen that the modification could have contributed to the accident, it is unlikely that the question will even be raised. Particularly with less common vehicles (such as Landrovers), where the police are unlikely to have any idea what original tyre sizes were offered. (for example, 9.00x15 was optional on most Series Landrovers and 6.00x16 standard for swb - 28" to 33" range!)

That said, my understanding is that most states have recently (last year or so) become very much tighter on lifts and tyre sizes, even when previously engineered, although as stated above, the chances of being picked up are pretty low.

John