I own a 2009 Cadillac CTS Coupe, which I purchased new. As delivered, while the trunk has a well to accommodate a donut spare, the car comes equipped with a compressor/sealer for repairing a flat tire on the road.
If I ever experienced a serious tire failure that the compressor could not fix, the car would require a tow, and couldn’t be driven without a new tire. I also suspect the compressor would only be a temporary fix, and I would need to replace the tire ASAP.
I could get a full-sized spare, but it would occupy almost my entire trunk. I might find an after-market donut (obviously need to match the lug pattern), but I suspect this could be a problem. The car normally operates as two-wheel drive (rear wheels), but automatically switches to 4-wheel drive if it senses wheel slip. If I installed a donut, given that tire’s much smaller diameter, would the car interpret this as wheel slip, causing the drive train to try to switch into 4-wheel mode? I suspect this would mess up the handling and put strain on the drive train. My guess is that Cadillac doesn’t provide a donut because the car can’t be driven safely with one. Is this true, or will a donut work in an emergency?