I’m currently running Kumho ECSTA STXs in 265-60-18 on stock wheels. I commute over 90 miles a day on these and am very happy with them. I have an extra set of stock wheels with Bridgestone Blizzak DM-Z3s in 265-60-18 for the snow. Worn tires will definitely result in poor handling, as will low and/or uneven tire pressures. Been there, done that.