What can you afford? If budget is a consideration, you should work out which size tyres you would like which are also common, that makes them mucho cheaper, then look for or make wheels to suit.

Obviously the rear will be wider than the front.

Keep them the same. You really want to be able to rotate your tyres front to rear often to make them last longer.

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And Saint Attila raised the hand grenade up on high, saying, O Lord, bless this, Thy hand grenade, that with it, Thou mayest blow Thine enemies to tiny bits...