Hi Manthan :). Sorry for delay in responding to your question. The bigger wheels at the back are the powered wheels that is why they are wider (just like the real thing). Where have your sketches gone? I liked them :).
We all live in a yellow submarine a yellow submarine... Great song and a great moc. I love all the details on the top and rear. I bet your grandfather is pleased with india's recent whitewash of England in the cricket :).