16inch vs 17inch rims , lower revs at higher speeds?

[pillzor]

i just changed over my wheels from walkinshaw rims too some 17s , the walkys were 16s and obviously put next too the 17s you could see there was an inch in diameter difference.
now since ive put the 17s on the car seems a bit slower and changes gears at higher speeds , this is obviously because of different wheel diameters... it also seems a little less punchy than it was.
my questions are:
how far will my speedo be out?
where the smaller rims making it feel punchier at the cost of more revs for the same speed?
cruising on the highway will i be sitting at lower revs?
all pretty much boil down too the same thing but im just curious , my stock wheels are the same diameter as the 17s that are on now so im thinking i may have been running lower size than recommended for a vs.

[axemurderer101]

Tire size calculator

try that

[VL-EXEC]

there wont actually be 1" difference, your rims size may change but your forgetting that your tyre profile also changes, which then corrects that 1" difference and will make it exactly the same (depending on the profile) or only have a minor difference 1-2mm...

and yeah your rite, say you have 20's the car is less "punchy" compare to 15's

[pillzor]

nah theres definately a size difference, side by side with tyres on them the walkys come up about an inch shorter in height.

[VL-EXEC]

then as i said, the tyre profile isnt making up for the difference

[pillzor]

yeh i get what you mean now, they were off a vl in the first place they must run a smaller profile.... so im guessing because my stock wheels are the same diameter as the 17s that my speedo will be correct now and would have been off with the 16s on it..

[venerableChicken]

assuming that they were 225/50/16's vs 235/45/17's there will be approx 1.2cm difference in diameter (height when beside each other, the 17 being taller) and around 1.9% difference rolling diameter. i.e. if your speedo was correct with the 16's, with the 17's, when your speedo was on 100km/h, you would be doing 102km/h