Wheels - the rules, the law and you...

[Lance B]

So let me get this straight, the tyre width can't be more than 26mm wider than stock, but there is no restriction on the size of the rim itself (so long as I match it with a low enough profile so as not to have the whole thing wider than 15mm from stock...

No, the tyre can be wider than the 26mm. The 26mm applies to the rim width.

26mm wider rim without the need of an engineers certificate.

You can go wider but you need an engineers certificate and these rules apply:
Up to 800kg = 26mm wider than factory
801 - 1200kg = 37mm wider than factory
1201kg up = 51mm wider than factory.

So I can go from 15" rims with a 4" profile tyre for a total of 19" of diameter to say a 18" rim as long as I can find a 1" profile tyre right?
*Numbers are made up for argument sake.

This has to *also* correspond with the speed and load ratings of the original tyre. So, if the originals are 95Y where 95 = 692kg and Y = 300kmh then you must fit tyres that are equal or better than these ratings. If the replacement tyre rim package fit the above criteria, then theoretically, yes you can do what you have suggested.

And that also means that for a VR6 who standard wheel is 6" / 6-1/2" wide you can only run a 7" - 7-1/2" tyre.

No, the *rim* can only be 26mm wider *than the largest optional rim width that comes as standard with that vehicle*, but the tyre can be wider than the 26mm allowable for the rim. So, the largest optional rim width for your car maybe 7" rims with 215 width tyres and you can opt to go aftermarket to 8" rims but you can go to 245 width tyres, which is a 30mm difference in the tyre width.

In other words, the law doesn't care if you want to run 20" rims with rubber painted on the outside, the problem is that they are too wide?

You can run 20" rims as long as they are no more than 26mm wider than the original rim width and that the overall diameter is no more than 15mm bigger (or smaller).

[Lance B]

Well that screws me with my RS's

FRACK that, they can come catch me lol.

What is wrong with the RS's? What are your original rims and tyres?

[schoona]

This is what I don't get.
The theme of "you get what you pay for" that runs everywhere should hold true. I mean, if you pay for H&R/FK/custom adapters, you can be assured (hopefully) of good quality design/manufacture > minimising/making negligible the added stresses on hubs etc....

Then it should be clear cut, yes adapters are safe, no they are not. It looks like VicRoads has the same stance as the RTA, but SA or WA may be different? Are they illegal in Europe as well?

As far as rim width goes, an extra couple of inches in width may not have such negative effects, if the rim is a lightweight design. Sure the COM may change and induce a different stress, but being lighter the difference is smaller, yet does not seem to be taken into consideration?

Ive got 18x7.5 with 215/35 on the Benz. I might be lucky on the diameter, but i don't think the other 190's had 6.5's. Only 6s. Unless Evo's are ocnsidered in this equation ??

[schoona]

What is wrong with the RS's? What are your original rims and tyres?

his originals are 15x6.5 with 205/50

can't rememeber his RS specs...check his build thread.

[linds]

If anyone wants to know what QLD cares for, it seems rim width is no issue, they are only concerned about the usual rolling diameter stuff, rubbing steering etc.

Here's the document: http://www.transport.qld.gov.au/reso..._vehicles2.pdf

[Manaz]

just for the boys that were interested in vicroads stance on this one. Seems much the same. The following PDF outlines what is permissible in section 8 starting on page 3 http://www.vicroads.vic.gov.au/NR/rd...340/0/VSI8.pdf

NSW RTA version here: http://www.rta.nsw.gov.au/registrati...vsi09_rev4.pdf

Tyre rules are mentioned there too - you must match manufacturers load index, and if you don't match the speed index you must affix a sticker to the windscreen saying as much. Which makes the 91V tyres I just had put on the car illegal, since the placard specifies 91W (speed ratings of 240km/h vs 270km/h respectively). I wasn't aware of this until I researched it just now... :/

[Shteifen]

not to quote Van Wilder or anything but...

"because i wasnt present then these laws were created, i reserve the right to bend them"



-steve

[DUBY]

Just read this and it all sucks, lol, I think I'm going to know my local constabulary on first name bases and it looks as if I'm going to have to have normal width tyres on the rears to save on the grief of being followed and stopped because of the obvious stretch, I wonder if I can away with the stretch on my fronts, 165 on a 7j, I think there a 7 any way.

[HaydEn]

I have 165/45r16et20 on a 7 with 25mm adapter on the front

165/50r15et20 on a 7 with 14mm adapter.

No problems. Cops love the have a good stare but not been pulled up yet

[DUBY]

RRRReeeeeessssuuuullllttttt