What is the biggest tire size you can use on a 15x7 in rim?

The biggest tire size you can typically use on a 15x7 inch rim is usually in the range of 225/70R15 to 235/70R15, depending on the specific vehicle and its suspension setup. However, some vehicles may accommodate larger sizes, like 245/60R15 or 255/60R15, but it's essential to consider factors such as wheel well clearance and overall vehicle handling. Always consult your vehicle's specifications or a tire professional for the best fit.