Spare Tyre Options for Australian GT

FPV GT · Jan 9, 2016

Bushranger said:
My understanding (?) is that the rear wheel, when mounted on the front will foul the strut (shock absorber). Hence the spacer to move the wheel further out and clear.

I read the Yanks are concerned about the brakes, however it makes sense that the shocks could get fouled.

Gnome · Jan 9, 2016

There is a bit of info out there, but without knowing for sure what is different between our cars and the US spec ones it is all a bit of guess work at the moment. You would expect the brakes, suspension and wheel well size all to be the same but.....
The other issue may be with different diameter wheels the ABS, stability control etc may also freak out, a lot of unknowns still but hopefully there is a viable solution.

thewolf · Jan 9, 2016

Without knowing the depth of the compartment the spare has allocated it isn't the easiest to work out the ideal width. I've played around on a site I found: http://www.willtheyfit.com/

This site calculates the rolling circumference of the tyre and factors in the geometry of the offset etc. Just playing with some numbers to find a similar circumference but significantly narrower to clear suspension and minimise protrusion from the spare storage

Except that I doubt it will fit over the brembos if required to be fitted to the front, a 225/60-17 has a circumference only 2.5mm smaller than the rear's 275/40-19 and is 5 cm narrower. Wheel and tyre can be had for under $300

225/55-18 is slightly more difference in circumference, pricing under $400. Not sure if this would clear the brembos up front

Once you start looking at 19" rims the prices start to climb and choices become more and more limited

Gnome · Jan 9, 2016

thewolf said:
Without knowing the depth of the compartment the spare has allocated it isn't the easiest to work out the ideal width. I've played around on a site I found: http://www.willtheyfit.com/

This site calculates the rolling circumference of the tyre and factors in the geometry of the offset etc. Just playing with some numbers to find a similar circumference but significantly narrower to clear suspension and minimise protrusion from the spare storage

Except that I doubt it will fit over the brembos if required to be fitted to the front, a 225/60-17 has a circumference only 2.5mm smaller than the rear's 275/40-19 and is 5 cm narrower. Wheel and tyre can be had for under $300

225/55-18 is slightly more difference in circumference, pricing under $400. Not sure if this would clear the brembos up front

Once you start looking at 19" rims the prices start to climb and choices become more and more limited

I have 4 pot Brembos on the GT and as far as I know there are a few 18" wheels that will fit, but no 17" ones. I am not sure if the calliper on the mustang is bigger or smaller but have doubts that we will find a 17" wheel that will clear them. But thanks for the info, the more of us trying to find a solution the better chance we have :thumbsup:

4stanger · Jan 9, 2016

to save anyone from trying, I have physically tried to place a FG Falcon space saver spare (17 inch steel rim) on the rear of my EB Mustang (same rear brake size as a GT?) there is only millimeters short of clearing the caliper, will NOT go on.

russ16 · Jan 11, 2016

Just wondering if the dealers might sell us one wheel/tyre from their stock of incorrectly supplied nickel lustre and black? Keep it as a spare at home for emergency?

HybridGT · Jan 11, 2016

russ16 said:
Just wondering if the dealers might sell us one wheel/tyre from their stock of incorrectly supplied nickel lustre and black? Keep it as a spare at home for emergency?

Factory wheels are staggered. So this would be a problem.

Unless you run a custom squared setup and buy 1 extra.

Gnome · Feb 4, 2016

Anyone know somebody that owns a Hyundai Genesis?
I believe that the space saver wheel from a Hyundai Equus with a 155/70/19 tyre fits over the brakes and also sits into the wheel well on the Mustang. Maybe the space saver from the Genesis is the same?

The PCD is the same but the centre bore is different but that can most likely be machined out to fit the Mustang.

I don't think the local Hyundai dealer is going to be open to letting me borrow a spare from one of these to test it though........

msweet · Feb 4, 2016

I'd be worried about getting a flat, then having an accident on a spare that's been machined to fit.

Can't see an insurance company being too happy about that

car · Feb 4, 2016

If you had a rim that fit the rear ok you could move a rim from the rear to the front in the event of a front flat. Bit of a pain to change two wheels but if you are on the Nullabore.....

Gnome · Feb 4, 2016

msweet said:
I'd be worried about getting a flat, then having an accident on a spare that's been machined to fit.

Can't see an insurance company being too happy about that

Only opening up the bore in the middle not changing the PCD which is the same on both cars. Plenty of wheels are now imported as blanks and machined to suit the required pattern of car they end up on, so not something new. If you used a spacer or had to use longer studs or .... then I would be a bit more hesitant.

I do see your point that insurance companies will use any excuse to get out of paying out, but I am comfortable with doing this if it fits, provided the tyre is also rated to the load. If others are not comfortable with it that is fine each to their own.

Gnome · Feb 4, 2016

car said:
If you had a rim that fit the rear ok you could move a rim from the rear to the front in the event of a front flat. Bit of a pain to change two wheels but if you are on the Nullabore.....

If only that easy.
The rears will not fit on the front, they hit the strut.

car · Feb 4, 2016

Gnome said:
If only that easy.
The rears will not fit on the front, they hit the strut.

oh. ok then back to the drawing board. Guess it will have to be one that fits the front...:doh:

Gnome · Feb 4, 2016

car said:
oh. ok then back to the drawing board. Guess it will have to be one that fits the front...:doh:

Don't beat yourself up I have spent hours on this so far, there has to be a workable solution, but to find it.........

car · Feb 4, 2016

Gnome said:
Don't beat yourself up I have spent hours on this so far, there has to be a workable solution, but to find it.........

too late already beaten up:lol:
got nothing to do at work trying to kill time before going home!

Spare Tyre Options for Australian GT

FPV GT

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Gnome

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thewolf

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Gnome

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4stanger

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russ16

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HybridGT

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Gnome

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msweet

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car

Car

Gnome

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Gnome

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car

Car

Gnome

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car

Car