I contacted my local dealer for a space-saver spare wheel and tyre and was given a 16” wheel with a 145/90R16 tyre. The car has 225/65R17 tyres. The difference in overal diameter is -57mm. This is a negative 8% difference in wheel diameter and way outside the +/- 2.5-3% difference recommended for normal safe driving.
Mazda technical department assure me that the 16” combo is correct and won’t do any harm to the cars trans-axle differentials or electronic monitoring systems.
However, wouldn’t it make far more sense to have a 17” wheel with a 155/90R17 tyre on it? This combo. gives an overall diameter difference of -2% which is within the recommended limits and therefore would appear the better option.
155/90R17 tyres are available from SpeedyWheels.co.uk of Derby as Maxxis M9400S 101M NS. These have a load rating of M101 (81mph / 825 Kg) and are sold as space-saver tyres.
Anybody got any thoughts on this or used the Maxxis tyres on their spare?
