225/55/ R16 tyres fitted instead of 225/45?/ R16

[NeddyBear]

After receiving some advise in here I purchased 4 of 225/55/R16 tyres for our VE Commodore steelies which are being fitted to our VX Commodore.
I thought they looked a little large and after fitting them to the front they fit very well but are about an inch heigher than the original 15's. Anyway I rang the tyre place but they won't take them back so I'll have to keep them on the car and what I need to know is where could I take the car to have the speedo tested so I can see what the actual speed is at 40,60,100 and 110klms.

[SweetWagon]

you can test yourself with a gps or timing yourself between 2 measured points

[showbags]

225/55/16 are a factory fitment on the Calais & statesman. I had the same combo on my VT Calais(225/55/16 on 16X7 VE steelies) without any problems. GPS was showing 99 with speedo reading 100.

[NeddyBear]

This is what I can't figure, others in here say 225/55/R16 is the correct size but the tyres that were on it when I purchsed the car 2 years ago are 205/55/R15 and I've never been booked for speeding during the last 2 years so maybe I was actually going slower than I thought.
I'll google the cars specifications to see what was the original size tyres: 205/65 R15 95H for 15 inch wheels and 225/50 R16 92V for 16 inch tyres.
So the other tyres I had were smaller and the new ones are slightly larger, I'll have to get one of those GPS things to see if its all ok and what is this GPS thing Fruit Loops mentioned.

[lout]

if your speedo was 100% accurate before, your new tyres will show 107km/h when you are actually doing 100km/h
services will also come around 500km earlier as your odometer will be out
holden can adjust your speedo with tech2 and i am sure any large shop with a scan tool should be able to adjust for you

[lout]

ok you posted another size whilst i was typing 205/55/15
if your speedo was 100% accurate before, your new tyres will show 97km/h when you are actually doing 100km/h
ie when your speedo says 100km/h you will really be doing 103km/h watch those cameras flash

[accentstencil]

This is what I can't figure, others in here say 225/55/R16 is the correct size but the tyres that were on it when I purchsed the car 2 years ago are 205/55/R15 and I've never been booked for speeding during the last 2 years so maybe I was actually going slower than I thought.
I'll google the cars specifications to see what was the original size tyres: 205/65 R15 95H for 15 inch wheels and 225/50 R16 92V for 16 inch tyres.
So the other tyres I had were smaller and the new ones are slightly larger, I'll have to get one of those GPS things to see if its all ok and what is this GPS thing Fruit Loops mentioned.

A GPS is one of those navigators you use instead of a street directory. They also display the speed your are travelling and they are quite accurate.

[som]

google "tyre size calculator."The original tyres on your car, ex factory ,were 205/65/15 unless you had factory 16" wheels fitted in which case they would have had 255/55/16's,Sooo you now have the correct size tyres for your rims and your speedo will be as accurate as the day the car came off the production line.The S came with 225/50/16's but had a recalibrated speedo.Whenever anyone considers changing rims and tyres from those that were fitted as standard equipment they would be well advised to google "tyre size calculator"then they will at the very least be making an informed decision that has nothing to do with dodgy advise from others who have made their own poor decisions.

[som]

I should have added.When you had those great looking (not really)205/55/15's on your car you were never going to be booked for speeding if you were sitting on the speed limit cos you were actually travelling 6.33% slower than you thought you were.