Track increase with 17x9 wheels

[sloba]

Hi,

And yes i've done a search and been reading all the information on rim & tyre sizes etc.

I've just ordered some 17x9 rims with a +20 offset for my 2012 ST which I will most likely fit 265/70/17 tyres to.

I believe the standard 17" rims are 7 inch wide with a +30 offset.

I've read the rules in WA state that you can only increase the track on a 4wd vehicle by up to 50mm.

I have used the calculator on the below website
http://www.1010tires.com/Tools/Wheel-Offset-Calculator#Results

The result is it says the outer position of the wheel will extend by 35mm.I assume this means each side..
Does this mean I mulitply that by two meaning my track has effectivly increased by 70mm and it is illegal or have i mis intepreted how this
effects the track?

The regulations stat as long as your wheel offset hasn't changed by more than 12.5 your track should be fine however I don't think that is taken into account the extra rim width...

If it is infact a 70mm track increase and illegal, whats your thoughts on extra stress on wheel bearings etc and am I risking my insurance or likely to be ok?

thanks in advance,
Mark

 

[sloba]

Actually are the stock rims 7.5 inch and not 7 inch?

However if they are 7.5 inch wide stock The calculator still says the new rims will extend an extra 29mm

 

[sloba]

Well I got the new 17x9 rims with an offset of 20 fitted up with Kumho KL78 265/70/17 and they fit all good, look way better as they poke out a bit more - pretty much flush with the guards or slightly poking out at the front not much though.

Now I just need a lift one day when funds permit.

 

[navaranewb]

technically you are increasing your track by 58mm however this will not be an issue for you too much

as for stress on your hubs etc this is next to zero as you are not jumping into the negative offsets and are not placing a huge amount of over hang on the studs.

just ensure you have the correct bore size and if not run hub guides and all will be sweet

 

[sloba]

thanks,

That was another issue I was going to bring up - the bore of the centre of the wheels is 78mm and my hub is 66.1mm I believe, im going to purchase some hub rings (which half of them look piss weak anyway) but I've researched these alot on the net and speaking to people and there seems to be mixed opinions if they are needed.

Alot of people say the hub rings (alot of which are made of plastic) are only to assist in ensuring the wheel is centred when mounting and this is there only purpose. They do not assist in transferring stress etc. I tend to agree after a bit of research as it seems to be the clamping force of the rim to the hub that does this. Surely a plastic or crappy alloy ring doesn't assist with this.

kind of 50/50 whether I really need them or not now but I think since they are pretty cheap I may as well just whack some on there...

cheers,

 

[navaranewb]

hub rings are a guide but will also stop any vibration that may occur with slack on the hub. I would def get them in this instance. S/S ones go for around 10$ a set if you look

 

[unkn0wn]

(running with the assumption stock is 7 inch by +30 and your moving to 9 inch by +20)

Track is measured from the center-line of your rim to the center-line of the apposing rim.

so if you have +30 rims and your moving to +20 rims you have changed your track by 20mm, compleatly within the 50mm limits of legality.

now if your changing your rim width from 7 to 9 inch rims, you need to look at it more like...
you have moved the centerline of the rim 10mm out, but you have increased rim diamiater by 2inch (50mm) so your new rim will stick inward a further 15mm toward the suspention components and 35mm outward of the body line, from your standard rim.

make sense?