VCDS adjustment for larger rolling diameter tyre?

[kaanage]

OK, not sure if this is the proper place to post but it seems to cross the boundaries of Wheels/Suspension, Electronics and possibly Tuning.

If I were to fit tyres with a slightly taller profile so the rolling diameter increased, can VCDS be used to adjust the odometer (and hence speedometer) to be aware of the gearing increase?

I've found lots of threads about adjusting the speedometer but none about adjusting the odometer - just lots of mentions that the odometer won't be affected if rolling diameter isn't changed when wheel size is increased by using appropriate lower profile tyres (duh).

[Transporter]

On some models yes, but it's impossible in T5 (maybe 2011 models are different). So, you have to check in the VCDS, I suppose.

[The_Hawk]

The setup in my T5 (and I assume lot of other VW's is a little odd).

The Odometer appears to be nearly 100% accurate, average speed, distance travelled and all that seems pretty spot on... the Speedo on the other hand reads about 6% over.

You can use this calculator to show what the difference's will be:
Tire size calculator

It's also worth noting that assuming a maximum 10mm wear from a new tyre your spedo can become out by up to 4% when running old tyres. So in my case I could have an odometer that was reading up to 4% over and a speedo reading 10% over when my tyres are completely bald.

[dylan8]

Id just leave it, i run smaller diameters on mine, and actually like it as it makes the speedo a round 10% out (easy to calculate on the run)
How much increase are we talking, post up your current and proposed tyre size..

[kaanage]

I'd like to go from the OEM 195/55R15 down to 185/60/R15 or 175/65/R15 and with these, I wouldn't worry since they'd only be a 1.3% or 2.1% increase, respectively.

But I may have more suitable tyres available in 185/65/R15 and that would be a 4.2% diameter increase and I'd prefer to be able to adjust this differential.

[T5Pete]

ALL new cars will run the speedo at 6%-8% higher than the real speed. this is an ADR I think now and covers them for different tire sizes and probably to make us all think we are speeding when we aren't. I always drive to gps on the freeway at 110 dead and am always overtaking people so i guess it works. Distance traveled is always spot on. the computer is doing it. on my new T5 I actually think it changes the % value depending on speed as at ~105 the needle starts to waiver about and i go from ~5% out to 8% out, but its a fat needle so you can't really tell.

I would not worry about it, it'll stop you getting flashed my cameras etc and when you get new hoops you don't need to do anything

[kaanage]

I'm now looking at getting 14" rims so that I can go down to a 165/70R14

This will make my speedo and, more importantly, odometer under read by about 1.5% so I'm hoping someone can help me with the VCDS adjustment to correct this

If I could get 165/75R14 tyres, then I'd leave it as this would gear my car up by 1.3% but nobody makes them (not for passenger cars, anyway)

[coastie]

Do you have the winter tyre adjustment available via MFD.

[kaanage]

Sadly no, on my Polo. I'm wondering if there is a VCDS fix for this.

I'm wondering if I have to settle for 175/70R14

[brad]

ALL new cars will run the speedo at 6%-8% higher than the real speed. this is an ADR I think now and covers them for different tire sizes and probably to make us all think we are speeding when we aren't.

I have a 2 month old Ford Mondeo sitting in the driveway & it reads 3% over at 100kmh (100kmh indicated is 97kmh actual). So did our 3 year old Calais.

I actually worked out the maths for the ADR in a thread on this forum once & asked if somebody could check it for me but the thread got locked before anyone had a chance to reply.