Mixing tire sizes and types
DON'T MIX TIRES OF DIFFERENT SIZES AND TYPES ON THE SAME AXLE.
For optimum handling and control, Dunlop recommends fitment of four tires of the same type and size unless otherwise specified by the vehicle manufacturer. FOLLOW THESE ADDITIONAL GUIDELINES: Fit newest tires on rear axle. If radials and non-radials must be fitted to the same vehicle, fit radials on rear axle. If tires of different profiles must be fitted, fit widest tires on rear axle. Never mix radials and non-radials on the same axle. When fitting snow tires or all-season tires to performance vehicles, always fit in sets for four. Do not fit tires with differing speed ratings. Never mix sizes and types on the same axle.
Broadly speaking, tires should not be mixed. It is recommended that all tires on a vehicle should be of similar tread pattern, same performance rating, size and construction, unless the vehicle was engineered for front and rear tires of different sizes.