How to correct speedometer for taller tires

[dlhovland]

I currently have 225 45 17 tires on my 2013 JSW TDI. I am going to 225 55 17 tires this week. The tire guid shows my speedometer will be of by 5 miles per hour at 70 miles per hour. Can I adjust this with my Ross tea. Thanks in advance.
David H

 

[JELLOWSUBMARINE]

No sure if your 2013 is the same as my 2011, but on my dash display it gives the option for 5% larger tire adjust.

 

[turbodieseldyke]

Your speedo is probably already reading "too fast" at 70mph, and "even more too fast" at 80 and 90, so bigger tires will make your speedo more accurate.

 

[dlhovland]

Your speedo is probably already reading "too fast" at 70mph, and "even more too fast" at 80 and 90, so bigger tires will make your speedo more accurate.

My digital speedometer reads one mile per hour fast at 70 miles per hour. Checked with gps.
my turbo diesel site has a write up on this if any body need help with this
David

 

[MK4TDIbew]

Perfect, just installed 205/70R15

 

[TurboABA]

Perfect, just installed 205/70R15

What does your 26.3" OD have to do with the OP's proposed 28" OD?

 

[TurboABA]

I currently have 225 45 17 tires on my 2013 JSW TDI. I am going to 225 55 17 tires this week. The tire guid shows my speedometer will be of by 5 miles per hour at 70 miles per hour. Can I adjust this with my Ross tea. Thanks in advance.
David H

 

[Jetta_Pilot]

VW for some reason, ostensibly to avoid speeding tickets, makes the speedometer read for example 60 Mph when you are really going less, up to 5% less at Kph or a different percentage at Mph, but your odometer will be correct.
When you install larger tires, as I have also done, the speedometer will be closer to accurate but now your odometer will be off.

To the best of my knowledge there is no way to adjust for that.

 

[hskrdu]

It's not a exactly VW issue. As has been discussed in prior threads, VW follows the Euro Union regulations (#39) which (in fewer words) states that the speedo can never read slower than actual speed. The end result is an odometer that is spot-on, but a speedo that reads high. It does seem more pronounced for German manufacturers, but that may be anecdotal. IME, it seems more notable in later year cars, but that may be a result of higher speeds than when I had a Rabbit or an air cooled Beetle.