225/55-16, 245/50-16, 245/45-17 and 275/40-17 will all have the same sidewall... which is why they work with the stock speedometer, the overall tire diameter is almost exactly the same.
The second number will need to increase to get a larger sidewall -- 275/40-17 (the aspect ratio, reads as a percentage of the width, in this case 40% of 275). When you do this you will most likely lose the accuracy of the speedometer.
A 265/40-17 will have less sidewall than a 275/40-17... 106mm vs 110mm sidewall.
A 275/45 or 275/50 would give more sidewall, but loose speedometer accuracy.
On a sidenote: a 245 width tire is in all reality too narrow for a 9" rim... you can run them that way, and there are many that do... but they stretch the tire and wont protect against curbs.
