No not the budgie smugglers !

I have recently fitted my new winter tyre and steel wheels, and having gone from 225/50 x17's to 205/55 x16's there seems to be quite an over read on the speedometer.

On a tyre size calculator the difference is only 3.81% so in effect it should only read 3.81 mph higher at 100mph.

Has anyone else made the same change ?

I have compared speed readings from the speedo and sat nav, which i am told is far more accurate.

Another thing i noticed is the average MPG has gone up, my average commute is now returning 65 mpg approx.

Oh these were supplied direct from Skoda and are the recommended size for the Yeti.

Surely yours should be 65 not 55 to have the same rolling radius?

Not an expert on Yeti tyre sizes, but 205/55 does seem too small.

A few people haven't been looking in TP's excellent guide!!

 

http://www.briskoda.net/forums/topic/148948-yeti-tyre-and-rim-guide/

 

205/55 are indeed a recommended Skoda size.

Yes I have read TP's excellent guide many times, beforehand. I am just curious about the different in speedo readings.

I have also found the winter tyres to create much less road noise.

I'm running 205/55/16 winter boots, and the readings are quite a bit more optimistic. A regular run I do on Thursdays that would get a reading up to 50mpg with the 17" Spitzbergs will get 53/54mpg on the 16s. The speedo shows 70 when GPS says 62, on the 17s the difference is only 2-3 mph. I've just got used to it now, and I have a winter formula in my fuel spreadsheet to take account of the smaller wheels. It's a small sacrifice for the extra grip that winter tyres give.

Same here, speedo's gone from being around 5% fast to about 10% according to the GPS.

I guess this will affect the mileage reading as well so the car will actually have done less than shown.

I've got 215/60 R16 winters, which are much closer to the 225/50 R17 summers.

Same issue, I got a great bargain set of used 205/55 alloys with tyres after checking carefully that these are a legal and supported size. When the tyres need replacing I plan to go up to 205/60 to resolve the problem of the diameter being smaller than my summer 17" wheels. Otherwise they are great. Pity it is not easy to change the speedo and odometer calibration.

205/55 are indeed a recommended Skoda size.

 

205/55 R16 is the only tyre size you can use on 16" wheels if you want to use snow chains on the front wheels (per owner's manual pages 211-212, May 2013 edition).  For that reason I have 205/55 R16s as my winter tyres.

 

I have calibrated the speedo vs GPS with both my normal 225/50 R17s and my 205/55 R16 winters.  The results indicate that the speedo is around 7% optimistic with the normal tyres, and 12% with the winter tyres.  (I keep a laminated hard copy of the table of results tucked in to my sun visor, and the key numbers quickly get imprinted on my brain when I switch tyres, so I don't have any problems keeping within posted speed limits.)

 

The worst error I have seen on the Maxidot mpg, compared to brim-to-brim calculations, has been 12% optimistic with normal tyres, 15% with winter tyres.  The least bad have been 5% with normal tyres, 8% with winter tyres.

And have you noticed how much better the ride is on your 205/55s? 

I've made the same change, noticed a similar over-read increase, and am enjoying the increased comfort with no noticeable change in handling.

I've got 215/60 R16 winters, which are much closer to the 225/50 R17 summers.

Same here.

With the 17" normal wheels and tyres, the speedo reads approx 10% over, so at indicated 70mph true speed according to GPS is 63.

With the 216/60/16's on, the speedo is less optimistic. At indicated 70, GPS speed is 67mph

Not sure what model everyone has but on my Elegance model there is an option in the Maxidot called "Winter Tyres" where you can adjust the speedometer to correct the difference between summer and winter tyres.

Anyone tried it - it should solve your problems!

Knew about that but don't use it for my reasons above.

IIRC the options are +5% or -5%

Not sure what model everyone has but on my Elegance model there is an option in the Maxidot called "Winter Tyres" where you can adjust the speedometer to correct the difference between summer and winter tyres.

Anyone tried it - it should solve your problems!

Sorry, but it doesn't alter the speedo, in any way.

All that setting does is to let you set an alarm for the speed rating of the winter tyres.

All explained in your Handbook.

And have you noticed how much better the ride is on your 205/55s? 

 

I'm not sure whether your smiley is intended to indicate that your question is tongue-in-cheek, but in any case: no, I've honestly not detected any difference in ride comfort.

 

The obvious handling difference - when there isn't actually snow about - is that the winter tyres give vastly better grip than the stock Dunlops when the road is wet, or you have to drive through standing water.

 

As for correcting the speedo error with different-sized tyres, AFAIK you can't do that even through VCDS.  I understand that it is possible to tweak the maxidot mpg calculation, but since the error in that is so variable anyway I'm not sure there's much point.

I have 215/60 R16 on my Freelander which came from my Yeti.

On the yeti they were slightly over size.

On the Freelander I should be using 65 profile so have the same issue now of under reading.

When I can afford to change if will put some slightly larger tyres on next time. Maybe 215/70 or 75 R16's