Reading all this ADR and tyre and rim assoc stuff has got me thinkin about getting a set of on road tyres (that is - small) for tooling around town (normally have 35s with 4" lift). Given all these rules and that my tyre placards unreadable, (says something like 16x6jj.):
1. what's the largest tyre legal on a GQ LWB wagon (completely legal, that is), i fear it may be 31s or 32s.
2. And for rims is it 7 or 8 inch (15s).
3. Does width make any diffence to diameter rules, eg can you run a 32x 9.5 s
instead of a 31x10.5.
Thanks, cause i did a search and tried to read the ADR rules and add 15mm but its all too confusing.
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Maximum legal tyre size for GQ
Within 100% legality varies form state to state and the interpretation of the law. QLD (usually the toughest state for this sort of stuff) allows a maximum of 15mm (0.6") from the maximum tyre size specified on the tyre placard.
For most GQ's that's a 7.5R16 which is 31.8" so 32.4" is legal. That means 32"s (normally about 31.6") are in but 33"s are out at 32.6". A 16" option to 32.4" would also be legal.
Eg 255/80R16 at 32.0 is legal but 255/85R16 at 33.0 is not. 275/75R16 at 32.2" is legal (hard to find but).
The biggest 100% legal I've found are Wrnagler Muds in 7.5R16 at 32.4
Depends on what you can find since not every option is available. most common are 265/75R16 (32"), 235/85R16 (31.7"), 285/70R16 (31.7").
305/70R16 (32.8" too big), 285/75R16 (over 33.1" too big), 255/85R16 (33.0" too big).
Starting to see the pattern? All under 32" or all over 33".
A simex extreme trekker 31x9.5 is kinda legal in that it's marked a 31" but is actually 33".
Some states will allow any tyre to the largest available legal factory fitment - so whatever biggest 31" or 7.5R16 you can find (probably a street legal swamper radial 31" or a Simex tyre) may be legal. So if you can find a 31" that measures 33" then you can use that to justfiy your 33" being legal. I know of people who have done this in NSW.
For most GQ's that's a 7.5R16 which is 31.8" so 32.4" is legal. That means 32"s (normally about 31.6") are in but 33"s are out at 32.6". A 16" option to 32.4" would also be legal.
Eg 255/80R16 at 32.0 is legal but 255/85R16 at 33.0 is not. 275/75R16 at 32.2" is legal (hard to find but).
The biggest 100% legal I've found are Wrnagler Muds in 7.5R16 at 32.4
Depends on what you can find since not every option is available. most common are 265/75R16 (32"), 235/85R16 (31.7"), 285/70R16 (31.7").
305/70R16 (32.8" too big), 285/75R16 (over 33.1" too big), 255/85R16 (33.0" too big).
Starting to see the pattern? All under 32" or all over 33".
A simex extreme trekker 31x9.5 is kinda legal in that it's marked a 31" but is actually 33".
Some states will allow any tyre to the largest available legal factory fitment - so whatever biggest 31" or 7.5R16 you can find (probably a street legal swamper radial 31" or a Simex tyre) may be legal. So if you can find a 31" that measures 33" then you can use that to justfiy your 33" being legal. I know of people who have done this in NSW.
Beastmavster wrote:Within 100% legality varies form state to state and the interpretation of the law. QLD (usually the toughest state for this sort of stuff) allows a maximum of 15mm (0.6") from the maximum tyre size specified on the tyre placard.
For most GQ's that's a 7.5R16 which is 31.8" so 32.4" is legal. That means 32"s (normally about 31.6") are in but 33"s are out at 32.6". A 16" option to 32.4" would also be legal.
Eg 255/80R16 at 32.0 is legal but 255/85R16 at 33.0 is not. 275/75R16 at 32.2" is legal (hard to find but).
The biggest 100% legal I've found are Wrnagler Muds in 7.5R16 at 32.4
Depends on what you can find since not every option is available. most common are 265/75R16 (32"), 235/85R16 (31.7"), 285/70R16 (31.7").
305/70R16 (32.8" too big), 285/75R16 (over 33.1" too big), 255/85R16 (33.0" too big).
Starting to see the pattern? All under 32" or all over 33".
A simex extreme trekker 31x9.5 is kinda legal in that it's marked a 31" but is actually 33".
Some states will allow any tyre to the largest available legal factory fitment - so whatever biggest 31" or 7.5R16 you can find (probably a street legal swamper radial 31" or a Simex tyre) may be legal. So if you can find a 31" that measures 33" then you can use that to justfiy your 33" being legal. I know of people who have done this in NSW.
Does it matter if I am running 15" rim or 16" ?
I am assuming 33" is 33" regardless of which rim its on. Like if I had a 33x15 alongside a 33x16 they would have the same rolling radius?
Nope... theoretically 7.5R16 should be 31" but it's more like 32" - 31.8" is the nominal measurement on most manufacturers websites... feel free to check around.
Later GQ's had 265/75/16 but it's still only a 32" tyre anyway so doesnt gain you an extra inch.
I'm relying on the arguement that a Wrangler TG 7.50R16 is 32.4" so therefore 15mm on that makes my 285/75/16 legal.
Of course the arguement that a Simex Extreme trekker 31x10.5x15 is 33.0" so you're allowed a 33.6" tyre could work
Later GQ's had 265/75/16 but it's still only a 32" tyre anyway so doesnt gain you an extra inch.
I'm relying on the arguement that a Wrangler TG 7.50R16 is 32.4" so therefore 15mm on that makes my 285/75/16 legal.
Of course the arguement that a Simex Extreme trekker 31x10.5x15 is 33.0" so you're allowed a 33.6" tyre could work
bought some plates for the GQ off a cop on saturday.
I asked him what the go is do they go off whats on the sidewall, or measured..
He said MEASURED. Whats on the sidewall means excrement.
Now, the normal pleb buys 31/33's and thinks he is gettin that.. Now he has to worry about taking verniers to the tire joint?
I asked him what the go is do they go off whats on the sidewall, or measured..
He said MEASURED. Whats on the sidewall means excrement.
Now, the normal pleb buys 31/33's and thinks he is gettin that.. Now he has to worry about taking verniers to the tire joint?
If it's got 31" on the sidewall I can't see how they can touch you - you've bought the exact tyre as per the placard so are totally ADR compliant.
If anything they have to address the issue with the tyre manufacturer, which is a legal reason why most tyres are well below their stated size.
The issue would come down to non specified sizes (eg 305/70/16). They should then be taking the tapemeasure to them.
Manufacturer specifications should be taken with a large grain of salt.
Remember also a muddy normally has 14mm+ tread depth. A fully worn muddy will therefore lose 28mm or over an inch in size - a very big difference and one of the reasons for tolerance in both tyre sizes and speedo accuracy.
Companies like Thornbird and Simex seem to measure their tyre sizes on a bare carcass or "bald" size when others measure theirs on full tread size. That's part of the reason for the big difference in size.
Whether it's a 15" or 16" rim does matter, as far as whats on the placard. They could do you for a 32x9.5x16 that measured 33", since it's over the maximum (non specified size, measure it - hey this is too big) but if you had a 31x10.5x15 (factory fitment) that measured 33" I dunno how they could touch you. You've fitted the specified tyre.
In the case of the Simexes their specified size is smaller in 32" than 31" so why would you anyway?
If anything they have to address the issue with the tyre manufacturer, which is a legal reason why most tyres are well below their stated size.
The issue would come down to non specified sizes (eg 305/70/16). They should then be taking the tapemeasure to them.
Manufacturer specifications should be taken with a large grain of salt.
Remember also a muddy normally has 14mm+ tread depth. A fully worn muddy will therefore lose 28mm or over an inch in size - a very big difference and one of the reasons for tolerance in both tyre sizes and speedo accuracy.
Companies like Thornbird and Simex seem to measure their tyre sizes on a bare carcass or "bald" size when others measure theirs on full tread size. That's part of the reason for the big difference in size.
Whether it's a 15" or 16" rim does matter, as far as whats on the placard. They could do you for a 32x9.5x16 that measured 33", since it's over the maximum (non specified size, measure it - hey this is too big) but if you had a 31x10.5x15 (factory fitment) that measured 33" I dunno how they could touch you. You've fitted the specified tyre.
In the case of the Simexes their specified size is smaller in 32" than 31" so why would you anyway?
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