Spare Wheel- One More Time!

[BC]

Ok sorry for beating this into the ground. Just want some expert advice from anyone so inclined on the forum. (can't get a reliable answer from dealer yet).

So here's my plan:
I have a GT with Performance Pack staggered wheels but traded my rear 19x9.5 wheels/tires for someone else's front 19x9 wheels/tires.
So now I have square setup 19x9 with 255/40/R19 on all four wheels, advantage being I can now rotate tires.

I now want to order the Spare wheel kit from Ford. It comes with the 18 x 5 wheel/tire, jack, wrench and retainer bracket.

My plan is if I have a flat on the rear, use the spare directly. The spare won't fit over the Brembos if I have a flat on front so I will do a switcheroo and put the spare on rear and use the good tire for front.

Here's my concern and it has been answered already on this forum with conflicting information. Does anyone know *for sure* that it is ok to run this spare wheel (smaller diameter wheel) on the rear and not damage the Torsen differential? (10 to 30 miles probably at the most, 50 mph and under)

I'm getting ready to order this tomorrow and just wanted to ask one more time if anyone knows for sure. (looks like it's $255 non-refundable from Ford, to place the order)

Thanks

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[BC]

The post in another thread below from ESP Jawa sounds reasonable to me but does anyone have any additional knowledge they'd like to share? Main concern is putting spare on rear and I have an issue develop with Torsen diff. where Ford says not covered under warranty because spare did damage.





This will destroy the Torsen if you drive very far.


No, no it won't. Assuming that you stay within the limits of the minispare's ratings (speed, distance), you won't cause any undue damage to the Torsen. They are validated for this sort of thing, and have been used in applications with pretty extreme tire size differences. In said application, it was tested for 300+ miles at 65mph. You do generate a bit of heat, so if you do this, you might eventually cook the oil. But the differential won't see any real damage, especially if you keep the driveline torque low. Drive sensibly and all.

That said, it might behave a little, um, quirky when driving with it on the rear. The differential will direct more torque to the bigger tire, which would make the car want to yaw toward the minispare under acceleration.
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[BC]

Ok...no posts from anyone for 2 days I guess means no one knows for sure about this.

I did an experiment and used the Ford site to 'build' a GT and found you can order the spare for any Mustang GT that has either 18" wheels or 19x8.5 wheels. You can't order the spare for 20" wheel option or Performance Pack (19" staggered) as we already know.

The fact that they let you order the 18" diameter spare wheel with a GT that has 19x8.5 wheels tells me there is no issue running smaller diameter as a spare along with a 19" wheel.

The only real question for me now concerns possible damage to the Torsen differential when running spare on the rear and possible loss of warranty to differential if damage occurs.

 

[Lagometer]

I just tried using the tire repair kit on the front of my GT PP. It was a complete failure. Ended up having it towed to the tire shop, now I wait for morning to speak with them.

 

[Sal33n]

People have been putting donut spares on cars for a long time. This shouldn't be any different. The point of a limited slip differential is to be able to have tires rotate at different speeds. If it couldn't you wouldn't be able to turn very well. Obey the speed and distance limitations and you should be fine.

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