runflat mix comments

Hi ! I went to my local Costco and asked for the price for two Michelin sp tyres for the rear, insisting I did not want run-flats.
They refused to sell or fit the new rears claiming that Michelin will not let them mix runflats and non-runflats even on different axles. I said I did not want 4 tyres as the front have tons of tread left I only wanted rears....
They claimed that the handling characteristics between runflats and non-runflats was dangerous when mixed??
Anyone had this comment made to them, I have never ever heard that there is such a difference as to be dangerous???//

Possibly a CYA in case someone tried to drive on a flat non-RFT.

While the vast majority of BMW owners who have switched from runflats to non-runflats, have been very happy switching away from run flat tires (non run flat tires tend to be more comfortable and longer lasting), they must be installed in sets of four for safety reasons; the run flat tire design has a much stiffer sidewall than a conventional tire and if mixed in axle sets can cause unpredictable handling. Also suspensions arew tuned for running these tires in sets of four. Hope this helps !

Don't do it!

http://www.michelinman.com/tires-101...lat-tires.page
http://www.tirerack.com/tires/tirete...jsp?techid=136