I've been looking into a GLA 250 for a while. This site has been a great resource. I finally did a test drive today and I was very disappointed with the handling. I think I scared the salesman when I changed lanes between to cars while accelerating. All four tires screamed and it almost felt like the car was going to role over, once when I changed lanes and again when I straitened out. Please tell me if this is just the run flat tires. Can anybody that has replaced the 18" run flats with decent all seasons tell me that the handling would be acceptable?