225/40-R18 tires are 0.47 inches (12 mm) smaller in diameter than 240/40-R18 tires and the speedometer difference is 1.9%
OFFICIAL B8 A4 Tire Thread *** [Archive] - Audizine Forums
993 NB max tire size - Rennlist - Porsche Discussion Forums
Tire Balancing Beads, Checkered Flag Kits - Checkered Flag Tire Balance Beads
The MICHELIN Commander II creates a new standard with regard to durability yet without making any compromises in terms of wet weather grip maneuverability or stability. This performance balance provides yet another eloquent illustration of Michelin's research and development philosophy: no performance gain to be achieved on one front to the detriment of another. Rubber compounds provide remarkable wet grip without compromising durability.
Michelin 24404 Commander II Rear Tire
240/40-R18 vs 225/40-R18 Tire Comparison - Tire Size Calculator
240/40-R18 vs 225/40-R18 Tire Comparison - Tire Size Calculator
993 NB max tire size - Rennlist - Porsche Discussion Forums
Tyre overall rolling diameter
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What Your Tire Size and Number Say
240 40 R18 Tyres – compare prices and buy affordable Tyres online
The list
Wholesale 205 40 18 Tires Products at Factory Prices from Manufacturers in China, India, Korea, etc.