From the Yoko website:

 

You can fit 245/40s to the standard 18" wheels. All of this is governed by ADR 24, which basically says you must ensure that the load carrying capacity and speed rating of the tyres are at least equal to, if not better than, the sizes shown on the vehicles ADR24 tyre specification placard.

Full, boring details follow:

Provided this is the case, then:
- fitting of replacement wheels (and suitable tyres) up to 26mm greater than the widest optional wheel offered by the vehicle manufacturer for that vehicle. The replacement wheels must meet the general requirements and must not increase the wheel track by more than 25mm when the original axle components for the vehicle are retained;
- The overall diameter of the alternative wheel and tyre must not be greater than 15mm over the largest diameter wheel and tyre specified for the vehicle and shall not be more than 15mm below the smallest diameter wheel and tyre specified for the vehicle.
- the rim width must not be less than the minimum width fitted by the vehicle manufacturer for the_ particular model,
- the wheel (and tyre) must be contained within the body work, or mudguards, which includes “flares” when the wheels are in the straight ahead position;
- wheels (and tyres) must not foul any part of the body or suspension under all operating conditions;
- the wheel and tyre combination must be in accordance with the tyre and rim standards published by the “Tyre and Rim Association of Australia”:
- the wheel must be one designed for the particular hub/axle in respect to both pitch circle diameter and wheel nut tapers. Wheels with slotted stud holes are not permitted:
- where the original axle components for the vehicle are retained, the wheel track must not be increased by more than 25mm beyond the maximum specified by the vehicle manufacturer for the particular model. Where non original axle or suspension crossmember components are fitted, the offset of the wheel in relation to the axle or stub axle assembly used shall not be increased by more than 12.5mm each side of the vehicle based on the specifications of the axle components used. If an axle assembly is shortened then the track limit is taken as the axle manufacturers original track dimension, less the amount the assembly has been narrowed, plus 25mm.
- All rims fitted to “an axle” must be of the same diameter, offset, width and mounting configuration (except for spare wheels used in an emergency situation);
- The wheel must not prevent the wheel nuts from fully engaging their studs;
- The rim must not have a circumferential weld other than that which attaches the rim to the wheel centre;
- Speedometer accuracy must be maintained for the selected tyre and rim combination to within the degree of accuracy specified in ADR 18/01 (+/- 10%);
- The fitment of wheel spacers (or adaptors for dual wheel conversions) between the wheel mounting face and the road wheel is not permitted unless fitted as original equipment by the vehicle manufacturer.


Damn -- I was thinking about dual rear wheels for the 8! :D

 

the stock 225's are a bit small for the 8" rim 235 is about right and 245 is a bit big for 8". all sizes will fit the rim but you might start to get more flex in your side walls with something they have to strech on or squeeze on. I reckon with a 245 on a 8" rim you will have the contact patch moving round in relation to the rim detracting from the handeling.

 

Hey the stupid Bob Jane I went to locally said in the size 225/45 only have RE040, Michellin Pilot Sport or PZero Rosso. More choice in 245/40 and the circum is 6mm diff...

 

Sorry Richard -- was that indicating that A539s are now available in 18", or that 245s will work on an 8" rim?

 

Timbo, check with your insurer b4 laying down any folding...

Gomez.

 

Taka, you're right, 225/45-18 is an oddball size and as a result is relatively expensive....

 

Sure will, but as I read the ADR, 245s are ok. Have you seen something that says they're not?!

 

No Timbo, just the Tyrepower info....But I've had insurers refuse to insure on the basis of tyre width before...even tyres of std fitment!!

Maybe its a Victorian roadworthy requirement that they were referring to.....

Gomez.

 

Oh yes, roadworthiness is an entirely separate issue, where State laws come into play…!

 

Sorry timbo, it was that 245s work on 8" to 9.5"

 

I am just updating this 'cos I obtained a few prices over the last week. These are 'inquiry' prices rather than those one might when haggling with a full set purchase in the offing.

First, both Bob Jane and Jax say 245/40s are ok on the 18x8JJ standard Aus rim (at least in the ACT)

Secondly, there's not much choice at present in the standard size -- 225/45 -- and they are expensive:
* replacement Bridgestone $475/tyre
* Pirelli $620
* Michelin $625

There's more choice in 235/40 but the circumference is only just within tolerance -- the speedo will be almost 10% optimistic, reducing the final drive and the rate at which Ks are clocked up.

I am quite keen on Yokohama tyres -- as noted above, you can't get A539s in 18" rim, so the selection is S306 -- on par with the standard Bridgestones; ES100 -- probably closest to the A539; and V102 -- best high performance/grip, but they wear quite fast

Prices 235/40 245/40
S306 $390 $410
ES100 $415 $465
V102 $440 $530

As we will all be facing this issue sometime, I wonder if we might create a 'sticky' with tyre prices so we can see where the best deals might be obtained. Don't need to stick to the above, just prices/observations.

Finally, at 25,000K, I reckon I have maybe 15-20,000K more life in my tyres.

 

I can hear my credit card groaning at these prices ... I may stick a print of this thread under the sunvisor to correct my 'give it a foot full' habits!

a new set of rubber equates to 4% of the purchase price ...

Memo to my career - time to consider working for Michelin!!!

 

if tyres are 4% of the cost, it makes you realise what a performance bargan you are getting in the rest of the car :D

 

IF I got 40 - 45k out of a set I would pretty happy. But the price of the new tyres! Ouch!

With the numbers of these sizes of tyres (i.e. 18") increasing (all the SS Commodores are now 18's, I would hope the prices come down some...

Cheers,
Hymee.

 

I reckon 40K is going to be tops, especially after Wakefield . It will be a handful in the wet after that.

Yes, that's one thing the tyre guys did say -- more 18" would be coming. And I reckon there is probably 10-15% discount available for a set price

 

Had to replace two P6000's on the XSI for the roadworthy , only got 35K out of them, so would be very happy with 40K on the 8.

Gomez.

 

I got 25k out of the 17" SO2's on the VT1 Clubby

 

hoon

 

Ahh - but the B510's on the SS were on there way to 40k

VT1 = 195kW
SS = 300+ kW

Cheers,
Hymee.

 

Mrs Hymee's SS..!

 

I got just on 50k km on the sti.
Dreadful indictment of creeping old age.

 

At 15k, I would have about 6-7k left on the rear tyres. I am prone to losing traction occasionally, however.

does this make me more or less on the tyre wear than the average?

 

I'd reckon that's somewhat lower than average, on the original spec tyres BTW, isn't your dealer rotating your tyres each service? Mine is, consequently wear is pretty even

 

Hymee,

How about making this a sticky?

Could be very useful as reference when we need to get new tyres.