I recently bought a 1985 BMW 735i. I looked at the tires and noticed a size i had never encountered before, 220/55VR390. I did not recognize the "390" part. It turns out that during the 80's Michelin worked with BMW and other car makers on a metric sizing design that did not last long called "TRX" wheels and tires. I will need to replace the tires fairly soon and it's my understanding that these tires are very expensive. My stock wheels are in great shape and I'm trying to restore the car to original specs so I'd like to keep them. The rims are 15.35" (390 mm). My questions to the forum are: (1) Can I mount standard tires on these wheels safely, (2) Where can I get TRX tires for a reasonable price, and (3) If I do have to switch wheels, can someone give suggestions for another BMW stock wheel from that era that would at least look original and where I can see pics of them. Thanks in advance for your input.