Speedometer reading based on 18" or 19" wheels?

[Obakong]

Does VW calibrate the speedometer differently for the base R with stock 18" wheels vs the 19" wheels that come with Nav/DCC?

Because the size of stock 18"s is 25.1" tall. And the 19"s are 25.5" tall.

Do the 19" wheel option already have a little speedometer inaccuracy due to the size difference?

I'm asking because I have the stock 18" wheels, and wondering if I change size if I should be trying to stay close to 25.1 for speedometer accuracy or 25.5


Thanks

 

[TheSwede]

Does VW calibrate the speedometer differently for the base R with stock 18" wheels vs the 19" wheels that come with Nav/DCC?

Because the size of stock 18"s is 25.1" tall. And the 19"s are 25.5" tall.

Do the 19" wheel option already have a little speedometer inaccuracy due to the size difference?

I'm asking because I have the stock 18" wheels, and wondering if I change size if I should be trying to stay close to 25.1 for speedometer accuracy or 25.5


Thanks

I ordered the Golf R with 19” Pretoria OEM wheels with tires 235/35 profile. The speedometer shows exactly the same speed as my Garmin GPS. 0% in difference, very rare.

I run 18” 225/40 on my winter wheels. The speedometer shows about 5 % to much at 100km/h (62mph) compared to the GPS. This is normal.

I’m convinced it’s calibrated for 18”.

/Peter

 

[phobos512]

The difference in revs/mile between a 235/35-19 and a 225/40-18 is 1.5%. At 60 MPH the 18s will show 60.9 MPH if the 19s show 60. Basically, it shouldn't matter.

 

[TheSwede]

The difference in revs/mile between a 235/35-19 and a 225/40-18 is 1.5%. At 60 MPH the 18s will show 60.9 MPH if the 19s show 60. Basically, it shouldn't matter.

In my case its about 4-5% speed diff.. I am sure. It's NOT the same type of tires (or brand) at all so there are for sure other differences to concider.

/Peter

 

[dr_mat]

There is no significant change in rolling radius between the factory wheel and tyre options so you should see no significant change to speedo accuracy whichever you switch between. There will be a bigger change between new tyres with high pressure and well worn tyres with low pressure, tbh.

 

[AR11]

http://www.wheel-size.com/calc/?whe...l2=235-35-19X8ET45&fcl=50mm&wcl=30mm&scl=50mm

 

[dr_mat]

Cool site.