4 Answers

i used to work for a tyre company who made a tyre that had less rolling resistance.to prove this they got two identical cars and fitted there own to one and another manufactures tyre to the other.the cars were rolled down a ramp and one car rolled farther .of course some clever clog in the audience suggested that the cars maybe were not so identical.the same tyres were swapped over and the other car rolled the furthest.so i think the answer to you question is yes,a tyre can change the speed slightly because of the type of rubber and also tread pattern.

sure!there will be less resistant!

DEPENDS ON THE SURFACE...AND ONLY ON ACCELERATION.

only if you change from the regional factory size tires, a taller tire will make your car show you going the same speed,but your faster then what you are. and just the opposite for putting on a smaller tire.