Hi Folks,

I was suffering from the universal sawtooth problem and attendant noise with the Dunlop SportMaxx tyres on my 2008 vRS CR so changed all 4 for Kumho Ecsta 225/45/18 tyres and had a 4 wheel allignent adjustment.

Just completed 1000 miles. Results are very pleasing. Much quieter, better ride, speedo is now 100% accurate (when checked with aftermarket sat-nav) and fuel consumption readout is also now correct.

The only downside that I can find is the odometer clocks the miles up about 4% too slowly (again checked over 250 miles with sat-nav).

I just hope the sawtooth problem doesn't reappear.

Cheers,

Mark

Is there any particular reason you fitted the wrong size tyres?

+ 1 what Pilotwoo said

Also the 45 profile tyres are approximately £20 each dearer than the 40 profile tyres.

Look here

http://www.alloywheels.com/tyrecalc.asp

I'm curious to understand the why. Did you let your insurance know your not running manufacturer spec'd tyres? What did they say? I ask because of the whole Winter tyre thing with some insurers charging extra.

I would imagine it was probably to increase ride comfort?

I did it to reduce noise and increase comfort - which they have done. I paid the same as 40 profile tyres of the same make.

My Vrs has 225/45 18 fitted as standard. It was a brand new car on 1/3/11. So how has he fitted the wrong size???

Standard tyre size for the VRS is 225/40/18 or 225/45/17, certainly pre FL. Are the new ones all coming through with 225/45/18 then? It would be odd for Skoda to supply some new cars with 40 and some with 45 profile as they would have a different rolling diameter.

Edited 12 March, 201115 yr by pilotwoo

2 of my friends both have facelift vRS's one a 10 plate the other a 60 plate and they came with 225/40 18 from the factory, so this is confusing?

My pre facelift also came with 225/40 18 tyres.

Edited 12 March, 201115 yr by Bogwoppit

I haven't read the specification to see what tyre sizes are accommodated or approved but just because the car comes fitted with one size of tyre would not necessarily imply that it is the only tyre which is approved would it? The very fact that there are so many variations of wheel and tyre sizes on factory produced derivations of the Golf V platform suggests that there is a lot of leeway. The insurance argument is a strong one though so I personally would need to be certain that I could prove my case if it came to it.

Yes it does. You need to keep the rolling diameter the same otherwise your speedo/odometer misreads, as per the OP. You can change the wheel size, as long as the profile is adjusted too to give you the same rolling diameter. For example the 17/18" sizing that used to be available on the VRS resulted in either 45 or 40 profile tyres respectively.

as far as im aware, you are now braking the law, and potentially would fail an MOT. The maximum difference between the OEM rolling radius and any change in tyres size is meant to be 2.5%. 225/45 tyres will give you a 3.5% difference.

you could have fitted any of these

Tyre code Diameter Circumference Difference

---------- -------- ------------- ----------

235/35 R18 622 mm 1954 mm -2.43 %

245/35 R18 629 mm 1976 mm -1.33 %

215/40 R18 629 mm 1976 mm -1.26 %

225/40 R18 637 mm 2001 mm 0 %

235/40 R18 645 mm 2026 mm 1.26 %

as far as im aware, you are now braking the law, and potentially would fail an MOT.

/quote]

Why would it fail an MOT? What part of the test checks the tyres are the factory fitment?

Edited 13 March, 201115 yr by juan27

My Vrs has 225/45 18 fitted as standard. It was a brand new car on 1/3/11. So how has he fitted the wrong size???

Are you sure?

Standard is 225/40/18....Always has been with 18" wheels on the Octavia

On the FL vRS you have the option in the maxidot to change the wheel setting for fitting slightly different wheel diameters when using winter tyres, I wonder if this is activated on some of the cars running the 45 profile tyres, if you have not got maxidot you would not know about this option

On the FL vRS you have the option in the maxidot to change the wheel setting for fitting slightly different wheel diameters when using winter tyres

Are you sure ?

I can see a winter tyres setting in my maxidot, but all it does is enable an audible alert if you go over a certain speed (you can also adjust that speed).

I defo have 225/45 18 on my FL vrs. Conti sport 2's

I can confirm the maxidot function for setting the rolling diameter too. I didnt use it for my winter tyres though because they were spot on when compared to GPS.

When I got my car it was fitted with 225/45 R18 and it passed an MOT no problem, I have since changed to 225/40 R18 as all the literature stated these were the correct size from standard, and the lower profile looks sooo much better, tbh no difference in ride comfort or handling that I've noticed.

Re-checked my tyres and they are 225/40 18. Easy mistake 