Thank you for confirming what I stated in my response on September 3rd:
“But, to return to the OP’s question–The reason why there is a well for a donut spare on this car is most likely related to the fact that this vehicle can be ordered with either AWD or RWD. I think it is likely that the RWD versions do have a spare tire, and that it is deleted on the AWD version in order to avoid mechanical problems resulting from owners driving long distances on a temporal spare.”
A lot of manufacturers now are eliminating spare tires to reduce weight and improve mileage. The current and upcoming CAFE requirements are driving this.
Consumers are not generally pleased. Many are also not pleased with the new “run flat” tires when they happen across the cost to replaced them
So some manufacturers are now stamping a “well” in the trunk floors and offering a compact spare as an option. This enables them to meet fuel efficienty standards while still offering a spare to those comsumers who would rather avoid those squirt cans…which can mess up theinside of the tires and are useless in the event of a sidewall tear.
Just to put this issue to bed, I received a phone call directly from Cadillac in response to my inquiry. The gentleman I spoke with (I assume he was from their technical side of the house) stated that the car CAN be driven with a compact spare without any issue with the car’s handling or possible damage to the drive train. Of course, he recommended I not drive on such a tire for an extended period. He was not able to clarify for me why Cadillac did not provide a compact spare with the car, but instead provided a compressor/sealer unit. I suspect it was either cost (the spare and jack cost more than the compressor), or a weight/milage issue, or both. Anyway, it’s okay to use a compact spare tire on this AWD car in an emergency. It still leaves the issue of finding one – as my research to-date indicates that they’re not easy to come by. Nevertheless, its okay to use one if I can get it (and at a reasonable price.)
I’m glad that you took my advice and phoned Cadillac at the corporate level.
Now, as to getting that donut spare mounted on an appropriate wheel, any tire dealer should be able to order one for you once he ascertains the size of the tires and wheels that are currently mounted on your car. It is even possible that TireRack.com can supply what you need.
You can always order one at your dealer if they do not have one in stock. Try a junk yard. They may have one that fits. You could also see if another GM car compact spare fits. You will need to know the dimensions of the CTS spare to make this work. That is, bolt pattern, rim size, donut spare dimensions.
Saving 60 or so pounds of weight in a car such as a Caddy CTS that weighs near 4000 lbs and saving a few dollars on a vehicle that is priced around the mid 30s and more is a boneheaded concept from Cadillac for some of us.
It may be possible that Cadillac believes that most of their customers would prefer to call for help rather than get a little dirty from changing a flat tire or else can not change a flat tire. The incidence of a flat tire is quite rare and the incidence of a tire that goes flat due to self destruction is also rare.
I have seen quite a few flats but have always been able to repair the tire myself or have it repaired by someone else. The Cadillac sealant and air pump kit would probably have always worked to get me back on the road but a compact spare seems more reassuring. The best option might be the sealant kit and pump with a compact spare, jack and lug wrench as a backup. A little larger spare tire well would hold all of this. Cadillac certainly has the room for the cost for these things in their pricing.