Costco has non-run flats on sale at the moment - depending on size 800-1000 for a set. Note that these are not 'M' rated tires. they are EV tires, and have about double the life of the OEM tires. So, they will not handle as well, but about 96-97% is my guess from reading about tires on other forums.
the OEMs are not EV specific. Mine came with Goodyear Eagle Sport all seasons, decent, not fantastic. I've never run Goodyears on a car. I compared them to Michelin, PIrelli - all about the same price within a couple hundred dollars a set. anyone have experience yet? I think I'm going with the P Zero
I once bought some blemished Continental tires. They stood up very well and I was told that were a very good brand. Maybe they would be worth checking out.
