Widest Legal Rim Size For Vicroads

[JiVE]

Hey guys,

Sorry if this has been posted before.

But does anyone know what the widest legal wheel and tyre size is for an R33 GTST?

I've looked up vic roads, and as confusing as it is something about 25mm from the stock wheel on the model, but i've been told it can be any model variation of the car so does this mean 25mm ontop of the GTR wheels sizes?

Thanks

[dezz]

there's a heap of rules with wheel sizes, but from what i learnt when speaking to vic roads (not for skyline however) its on the largest factory option.

Now, with the fords, eg, the AU series, they used to include the XR's. so basically, XRs had the 17" option from factory, so that meant the standard falcons with 15 or 16 inch rims could use the XR spec largest option and get bigger wheels that way.

not sure if they do it the same way for 33 GTS-T/GTR, but they could probably tell you that 1 if you rang and asked it specifically

[Coupe-This]

Dont ask vicroads, they know shit, well if you talk to 5 people you will most likely get 5 different answers. In regards to wheel sizes. You may not go more than 1 inch (25mm) wider and no more than 15mm bigger in total rolling diameter. So in regards, if you look at the fords as dezz made an example of. Im sure the standard falcon with 16's or 15's (shrugs) has higher wall tyres than the xr's to keep the same rolling diameter. But i could be wrong, dunno for sure.

Ring up an engineer, and he will explain to you that you cannot change the trackwidth of the tyres.

Thats about it. Good luck

[dezz]

yeah, most people think that the rule is 2 inches bigger (diameter) than the largest factory option, but the guy i spoke to at vic roads gave me the detailed rules, and its all about maintaing the same rolling diameter (or staying within the limit which is like 15mm as james said)

thats why you have to lower your tyre profile the bigger your rims are...

[JiVE]

so what then is the max tyre profile? 225?

[Coupe-This]

well the tyre profile, 225 + 15 = 240, whats the gtr wheel sizes ??? u would get away going on the gtr tread sizes

[riggaP]

My tyre placard (stuck on by compliance dudes) states that wheels up to 18x9.5 with 255 rubber can go on. I assume this meets ADR requirments...

[JiVE]

Thats weird then, that dosn't match the vicroad specs?

[Ronin 09]

well the tyre profile, 225 + 15 = 240, whats the gtr wheel sizes ??? u would get away going on the gtr tread sizes

<{POST_SNAPBACK}>

Coupe this - that's not how profiles work

so what then is the max tyre profile? 225?

<{POST_SNAPBACK}>

Jive - that's the width...

I don't get what either of you are talking about.

profile is a percentage of the tyre witdh:

eg. 225/50/16 will give a sidewall height of 50% of 225 = 112.5mm

and if (for arguments sake) a tyre size is:

385/35/18, the sidewall height is 35% of 385 = 135.75mm

Therefore, "low profile" does not always equal skinny side walls.

Example:

stock skyline R33 gtst tyre size is 205/50/16 (by memory)

therefore total rolling diameter is:

16" ----> 406.4mm

add sidewalls (two sidewalls) = 2 x 205 x 50% = 205mm

equals 611.4mm.

if then you go to an 18" wheel, you will have to drop the profile to match the rolling diameter, working backwards

say we want to fit a 235 width tyre:

18" ----> 457.2mm

therefore the sidewalls must be 611.4 - 457.2 = 154.2

therefore each sidewall is 77.1mm

as 77.1mm is a percentage of the width, the profile is 77.1/(tyre width)

profile = 77.1/235 = 32.81%

However, as tyre profiles are in 5% increments, you must use a 35 profile.

As a 235 doesn't come widely in a 35, the fitment is a 40 profile.

[TracidTrax]

i remember trying to get road worth for my car and one guy wouldnt give it to me cause my rears were too wide, though when i went to another guy he didnt even mention it and still gave me roadworthy so ye its always a different answer

[xRHETTx]

Widest legal rim is largest factory rim width plus 1 inch.

You can go as large in diameter as you want, as long as the overall diameter of the wheel and tyre doesnt change by 15mm or something, cant remember exactly.

Look it up on the vicroads website