Question about tires

[p.smith78]

I have just purchased 2 Kumho ECSTA Supra 712....205/50ZR17 tires for the front of my car. The front tires were shot. The rear tires still have about 5000 K's left on them. The rear tires are Pirelli 255/40ZR17 Pzero's.

My question is....is it OK to run the Pirelli's on the rear with the Kumho's on the front until the rears need replacing at which time I will replace them with the matching Kumho's? Or, do I have to replace all 4 to have the same brands front and rear?

There are numerous reasons I went with the Kumhos instead of the Pirelli'$ $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ $$$$$$$$$$$$$$$$$$$$$$$$....Things are very expensive here in Canadaland, so the question isn't should I have stuck with Pirelli's, just can I have the two different ,manufacturers on the vehicle at the same time without causing any harm, or should I buy the rears at the same time. I have already bought the Kumho's for the front.

Thanks for your help.