These are wise words to follow. You don't want to screw around with rolling radius on an AWD car. You WILL cause damage to your differentials, with remarkably little change in different rolling radius. If you go up to a 40 profile, 245 tire, your diameter will increase by almost TWO INCHES, and this will result in damage to your differentials. Even going up to a 245/35 will increase your diameter by a full inch. Don't do it, unless you plan on converting your car to a rear-wheel drive anyways.....If this is AWD I’d think twice about changing tire sizes without properly calculating what you need in order to not ruin your AWD system.