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417 Posts
Discussion Starter #1
Hey all,
Just wondering what 18 x 8 with 225/40's would do to the speedo if anything?
Anyone have any ideas?
Thanks!
 

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Original fitment Proposed fitment

width 205 mm width 225 mm
aspect ratio 50 % aspect ratio 40 %
wheel diameter 17 in wheel diameter 16 in
offset 55 mm offset 55 mm

original diam. 25.07 in proposed diam. 23.09 in

Potential Fitments: Geometry Calculations:
tire aspect wheel change in ride height -25.2 mm
10.0 mm
+1 225 40 18 outwards add'l width req'd 10.0 mm
+2 235 30 19 add'l total tire height -50.4 mm
+3 245 20 20 add'l vert clearance req'd -25.2 mm

Instructions: additional rolling diameter -158.3 mm
Change values in boxed cells change in drive ratio -7.9 %
to see effects of tire fitment
changes. Unboxed cells show Speed Calculations:
resulting geometry. Hold the speedometer reading actual speed
cursor over inputs or results to 100 kph or mph 92.1 kph or mph
view associated pop-up help. desired speed speedometer reading
Note to TRX owners: 100 kph or mph 108.6 kph or mph
TRX 390 mm = 15.35 in.
 

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Discussion Starter #5
Hey, followed that link, thanks heaps for that, and it says my speed will be out 0.1%, when my speed says 60km/h I will actually be going 60km's/h... phew!
I just got my licence back like 6 months ago.. I dont want to go back mama!!
 
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