diameter of rims?

is it true if u change your tyres and they are smaller then your originals it can affect your speedo? and how would u go about figuring out how much your really goin because i plan to get different rims but then i wouldnt know how i would b actually goin..?

Keep the same rolling diameter.

how would i work that say if i have stock rims which are 14s and they are 60s and i purchase 17s what shud it be?

say if i got bigger rims and tyres and i were travelling 100km on my speedo would i b goin faster really?

I would say that if your speedo said 100, you would be doing about 140 with your above hypothethcal.

thats a big difference but i think it b goin that much

yt put it out byt like 2k on my mates pulsar

I don't know which of the above 2 posts make less sense.

I was kidding about the 100 - 140km difference civic86.

check this link out - its a tyre size calulator. Simply insert your stock dimensions , then insert the likely aftermarket - and you can see by how muhc it will reduce/increase your wheels circumference and thus the travel.

TYRE CALCULATOR

thanks for replys i already knew u were joking hoffman lol

For 17 inch rims, if you got 40 profile tyres, you would be going 103km if your speedo read 100 and if you got 35 profile tyres, you would be going just about 100 if your speedo read 100. Thats going by the assumption that the rims were 7 inch wide and you were using 205 tyres.

Keep in mind tho that speedos on aussie cars can have up to 10% variation btwn actual speed and indicated speed according to ADRs so the estimates are if your speedo was 100% accurate, in reality most cars are going about 95-98km/h when their speedo reads 100 with stock tyres so the difference larger tyres made wouldn't be that much of a problem.

that only applies with cars with wheel speed sensors doesn't it?