oversize wheels affect speedo?

[krisby]

I am hoping to get an LS400 when my business sell soon, I want to change the wheels too as the standard 16in wheels look naff.

However, do 18+ wheels make the speedo inaccurate? 18s might just be ok on a lower profile, but the rolling radius on 19s must be quite a bit different.

Anyone know or had problems?

 

[LexARSE]

I got 20's on my LS and there is a bit of a difference but it shouldnt really matter to much. Get a mate with a newish car and drive beside him on the free way when he's doin 100kmh and see what your speed is, then you know how much your speedo is out

 

[xirforever]

It doesnt matter one what rims size you have, all that matters is the overall tire diameter. So if you keep the same overall tire diameter on your new wheels then your set!

 

[krisby]

yeah but most of us would be increasing the diameter, wouldn't we? the LS400 I have here has little 16inch, admittedly on quite a thick profile, but the wheels do not fill the arches very well, so I would want to increase the rolling diameter to fill up the arches, unless I can find a reasonable conversion kit and have it lowered.

 

[xirforever]

i noticed in your other post you wanted some batter handling... so you can do all this, the wheels and handling in two moves, get the wheels while close to stock tire diameter and then lower the car. It will handle a lot better, youll fill in that arc space, and you will have the wheels you want without affecting spedo too much

 

[monkey]

ive got celsior/ls400 with 20's and my speedo is more accurate than the stock wheels
i have checked this with a handheld gps unit thats accurate to 2 decimal places.
stock wheels the clock showed 100 kph while true speed was around 96kph while the 20's with 235/40 profile rubber is much closer at around 98.5kph actual speed

 

[Muzza_NZ]

manufacturers always build a safety margin into the speedo - usually about 5km @ 100k

 

[sideshow]

i have electronic speedo adjusters for sale

i use them often to adjust tachos and speedoswhen i wireup conversions