I have put in some work on this G8 spares for C5's issue and have come up with the following which I hope may help those looking for a solution to the spare tyre problem. I have fitted an alloy wheel, this one, from a Holden HSV Monaro



which is the same as the G8. This wheel came with a 145/70-17 Goodyear tire which is 24.99 inches in diameter. I obtained a space saver tire for a standard model Holden Monaro which is a Goodyear 155/80-17. This tire is 26.76 inches in diameter. The C5 rear 275/40-18 is 26.66 inches in diameter. One tenth inch difference is acceptable. When fitted to the G8/HSV spare wheel which has the center hole turned out to 72mm to clear the hub spigot on the C5, there is no issue with diameter for the rear differential, there is clearance for the calipers, and the stud issue is acceptable for low speed, short distance emergency use. I hope I never have to use it but if I do I have my Porsche 928 jack which fits under my car with a flat tire, a wheel and tire combo that fits, won't fry the clutches in my diff, doesn't need spacers and will get me to a better location. I think this is a viable option to the slime/goo cans and plug kits. The only downside is it takes up some room in my trunk and there is barely enough space for the top when lowered.

 

Used it once...good stuff!

 

I hate to resurrect an old thread but I thought I would add and find it interesting that through all the threads I found about the "Z06 Inflatter Kits" sold with the Z06's that nobody stumbled onto the fact that, "these kits are NOT compatible with the stock GM TPS's used in other non-Z06 corvettes!" I will repeat that...goto GM's website or any place really and you will find that the Z06 non-runflat tire does not use the same type of valve stem/TPS monitor system that the non-Z06 models do with their EMT tires. This is why Z06 can use that latex slime stuff GM puts in that kit...that is just like a fix a flat goop. Z06 models did this to shave weight any way they could.

 

I carry a couple pieces of 2x8x10 along with a low profile scissor jack from AutoZone. If I have a flat, I'll roll forward onto the 2 xs and then have clearance for the jack.

 

I used fix-a-flat on one of my tires on a 2000 coupe. I did have to replace the tire pressure sensor after the tire was fixed. However it did get me the 50+ miles to where I got the tire repaired.
The issue is the tire sensor has a small hole in it that lets it read the pressure in the tire. If that gets plugged the sensor fails.I guess it would depend on a long the gunk remains in the tire ? After all the idea is for it to plug a hole so the tire holds air.
I have since bought a receiver and set of newer tire pressure sensors. Cost will be half what the 2000 sensor is plus the added bonus that the key fob works much better !
As for the jack I took the Vette to a wrecking yard and tested scissor jacks until I found one that fit under the car ! I now carry a GTO spare when I make road trips !
Getting stuck in the middle of nowhere texas is a bitch.....

 

I've used the slime brand fix-a-flat and the sensor continued to work for over a year until I finally had it changed out cause the batteries died. I would think that the fix-a-flat could cause problems if it plugs the pressure sensor, but in my case that didn't happen.