Indeed, blue has a good point. If the race is based on arriving at the end of the street, not on the top speed of the bike.
But even then you have tyres sized and inflated for your weight. Your friend has tyres sized and inflated for his weight. You swap bikes and you both have the wrong size and/or pressure in the tyres. One overinflated and one underinflated. Having underinflated tyres is worse for your rolling resistance than having overinflated tyres especially on smooth paved road.