Tyre legalities?

[predator]

Just a quickie..

Do you have to have the same dimension tyres on the back and front of your car for it to be legal? Same rolling diameter, just different width?

I want to put 205/55R16's on the front, and have 225/50R16's on the back.. just wondering whether it will be legal as i'll have to get a RWC soon.

[KamikazeR33]

i have 235s on front and 255s on the rear and ive had no problems

[rs73]

I don't think it should be a prob if you have a RWD car. As long as you don't mix tyre size on the same axle. But if you have 4WD/AWD, then you need to have the same tyre size all around.

PS: Is there a reason why you don't want to put 225 all around?

[predator]

Long story.. I've got 6x stocky rims, and 2x of them have different tyres on them. 2 are going to somebody else..

so sounds like its all ok. Thought it would be but wasn't sure. Thanx !

[Duncan]

no idea if its legal in VIC or not, but I run 235 front and 265 rear, works well.

The rules in NSW talk about rims being no wider than 1" over stock, but they say nothing about front v rear. And I think some of the big mercs etc come with wider tyres at the back from the factory.

[rs73]

I read this somewhere in the lines of RTA / Vicroads vehicle modification guide... On the top of my head: (correct me if I'm wrong)

Well, the idea is if rims are limited to a max of 1" wider than stock, this is to prevent ppl from putting tyres that are too wide that may cause the car to tramlining in the wet, instead of improving performance. As said before, there are no limit for the rim size providing you still got enough space in the wheel well.

It would also be a logic that tyres should follow the width of the rims, which means approx a maximum of 1" wider than standard tyres are also allowed. Then also tyre manufacturer has recommended rim width for each tyre size, so you can't put a 245 wide tyre on a 6" rim as it may reverse the performance of the tyre. (I'm talking about street tyres here, race/drag spec tyres may have some rules of exception)

The circumference of tyres are also limited to max +/-15mm from standard in order to keep your speedo accurate within reasonable amount. Therefore increasing tyre width require you to choose lower profile to prevent increasing your tyre circumference by more than 15mm.

[enilyks33r]

The NSW rule is that the front tyres must be at least 70% the width of the rears, this is to prevent drag style narrow front tyres being used