What does this simple rebus mean?

If a wheel has 54 spokes, how many spaces are there between the spokes?

Decode the below four famous ciphers:

8P of the SS
1M of the E
1S of the SS
60M in 1H

A famous swimmer can swim downstream in a lake in exactly 40 minutes with the lake current.
He can swim upstream in that lake in exactly 60 minutes against the lake current.
The length of the lake is 2 km.

How long he can cover the distance of one side at a still lake with no current?

Can you find out the missing number?

? 4 5 3 5

9 5 7 10 3

The centre of the third figure is empty. What digit should fit inside?

What has no start, end, or centre?

Using Only Five 5's and any mathematical operator make sum as 37

You can hear me, but you can't touch or see me.

What am I?

You board a train. The train will have to enter a tunnel soon. You are claustrophobic. Which place is the best for you to sit?