How far can i go with tyre size, 79 series standard rims.

phs

Well-Known Member
I have a 2014 GXL single cab and am in NSW , I had to go to an 8 in wide rim to be road worthy to fit a 285 wide tyre , I fitted 16x8 ROH octagon rims and BFG Km2 285/75/16 tyres .The increase in tyre size diameter lifted the vehicle by 28 mm compared to the tyre size on the tyre placard on the door jamb so if I want a 50mm / 2 inch lift I need an engineers certificate as any increase in lift over 50 mm has to be certified .In my case I would have lifted the vehicle 78 mm . In NSW they only allow TOTAL lift of 50 mm without engineers certificate ,so you could go a 50 mm lift and not need certification as long as you didn't increase your tyre diameter .

Not really awear of NSW laws but your tyres increased your lift by 28mm that's a 56mm bigger rolling diameter are you sure you can increase your tyre size by more than 50mm OD ?

That said it's debatable if you could use STD work mate tyre OD as it is bigger than the other models

In Vic it's 50mm suspension lift and 25mm tyre lift
 

abw

Well-Known Member
if I want a 50mm / 2 inch lift I need an engineers certificate as any increase in lift over 50 mm has to be certified .In my case I would have lifted the vehicle 78 mm . In NSW they only allow TOTAL lift of 50 mm without engineers certificate ,so you could go a 50 mm lift and not need certification as long as you didn't increase your tyre diameter .
Umm no that's incorrect. To self certify (no eng cert) in NSW, you can do a suspension lift equal or less than 1/3 the wheel travel...most interprate this as 2". In addition, you can increase your wheel diameter by 7%. There are other restrictions for wheels, like no more than 25mm wider than what's stated on the tyre packard, and no more than a 50mm increase in your track (eg. standard rim offset on my car is P10, so legally I can go up to -15mm). Pretty sure this is now the case in most states now.
 

Aussiehunter69

Active Member
Umm no that's incorrect. To self certify (no eng cert) in NSW, you can do a suspension lift equal or less than 1/3 the wheel travel...most interprate this as 2". In addition, you can increase your wheel diameter by 7%. There are other restrictions for wheels, like no more than 25mm wider than what's stated on the tyre packard, and no more than a 50mm increase in your track (eg. standard rim offset on my car is P10, so legally I can go up to -15mm). Pretty sure this is now the case in most states now.
Your are correct in relation to the wheel travel .So you can go the 1/3 wheel travel plus the 7% increase in wheel diameter and not need certification ?So if my original tyres are 777mm in diameter how do they calculate the increase ?the RMS VSI6 in the tyres & wheel section uses and example original tyres 712mm diameter if you go to a 776mm diameter tyre which is a 64mm increase or 8% ...how do the calculate this ? 712mm x8% is 56.96mm ???Anyone?
 

abw

Well-Known Member
no worries. You multiply your standard wheel size by 1.07. Should not be higher than this result.
 

George.d

New Member
285/75 should fit with a 2 inch lift if you ask me. You may even fit 305's but this would increase the fuel consumption. Run'away down hill was not an issue when I had the 305's fitted.
Old vehicle running 305's
SHM_8485 by Scott Murray, on Flickr

New Vehicle running 285's

Untitled by Scott Murray, on Flickr
Hey Scott, I know this reply is a few years late but I’ve just purchased a new cruiser same as your graphite one and wanting to put 305s / 35s on her. Everyone keeps saying that you can’t put those tyres on the gxl rims because you’ll destroy your tyres and things could go wrong and that I’m better off getting new rims and putting a negative offset on?
Did you have any trouble fitting your tyres, and how long did you have them on her for?
And finally what tyre brand, because yours looks perfect!
 

phs

Well-Known Member
The tyre manufacture won’t warrant a 305 tyre on the std GXL rims which also makes them unroadworthy

but plenty of people have used unto 12.5” width tyres on the STD gxls

my advise sell them ( they fetch good coin ) and get a 8-8.5” rims

Looking at the photo from your attachment the tyres are BFG KM2s
 

George.d

New Member
The tyre manufacture won’t warrant a 305 tyre on the std GXL rims which also makes them unroadworthy

but plenty of people have used unto 12.5” width tyres on the STD gxls

my advise sell them ( they fetch good coin ) and get a 8-8.5” rims

Looking at the photo from your attachment the tyres are BFG KM2s
Awesome man thanks for the quick reply. I pick the car up next month - have been quotes for a 4 inch dobinsons mrr lift so they reckon I could fit 35s but it’s the rims that might be the issue. But then looking at the photo above I don’t have a bull bar so now I wonder again if I can truely fit or not as I won’t have the clearance a bar does?
What do you think ?
 

phs

Well-Known Member
I have an old build thread on my 79 series on this forum, had 35s with 0 offset on the front, the bull bar return into the guard needed trimming ( uneek bull bar ) minor job
 

George.d

New Member
I have an old build thread on my 79 series on this forum, had 35s with 0 offset on the front, the bull bar return into the guard needed trimming ( uneek bull bar ) minor job
Awesome I’ll look into it more! Appreciate the help!
 

AJ 123

New Member
You don't get runaway with 35s on a 79 series 285s will not be an issue, the gearing is all good.

If you are concerned about legality best do your home work and don't take some one from a forums word for it

in Vic you have 50mm tyre increase if you go by a workmate tyre placard
running 285/75r16s are fine

Go by the GXL placard there not read the wording on the tyre Reg document interpret it as you want.

I'm happy running 285s daily on my GXL factory alloy rims. No idea why procomp are fine with 7" rim on there 285 but they do who am I to argue.

You could also look at 275s they are becoming more common now

Also 255/85r16 are another option
Hey phs,
Were you able to fit the 285/75/16 with the stock suspension? Need to replace my tyres first and then will do the suspension and GVM upgrade when I get back from a trick. Alternatively I am aware that the 285/70/17s fit and is more then likley what I will do otherwise. Would be nice to have the extra height however.
 
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