Safe? 215/55 front, 225/50 rear 300E???

[Bill '90 300E]

My car needs a state inspection and I have just discovered that one of my rear tires will not pass and the other is very close to not passing. The fronts still have considerable life left. My question - can I safely install and run 225/50s on the rear until the fronts (215/55s) wear out? At that time I'll put the 225/50s up front as well to even things out. I know the rolling diameter is almost a perfect match with the 215/55s and the 225/50s and will temporarily, at least, give me a "staggered" setup. Any input, other than to tell me that I should have rotated sooner (sic), is appreciated.