Hi all,

 

Would there be any issues with fitting a 45 sidewall tyre to an 18" alloy on a MKII? Standard size is 225/40/18. The difference being a 22mm increase in diameter  ...

 

I'm certain of two things

 

1) The speedo will read slightly higher

 

 2) It will effectively give the car slightly higher gearing (better economy on long runs)

 

Will this affect any speed sensors etc?

 

Thanks in advance,

 

Rob

http://www.4x4tyres....t33klscmo7pckc5

OK. Put the size of the tyre you have now on the left wheel of this tool. And adjust the right to the size wheel you want to fit. It gives you all the rolling road dimensions. It also tells you how far out the speedo can be with different profiles.

Used this loads of times to show range rover owners the difference between 16 to 20 inch wheels.

Hope it helps.

Dave

Sent from my SM-N9005 using Tapatalk

Sent from my SM-N9005 using Tapatalk

Sidewall alone does not give any info. How wide new tires will be?

Brilliant Dave thanks a mill.

 

LS108, thanks for the reply. The exact tyre size will be 225/45/18, the only difference being an increase in sidewall from 40 to 45 ..

 

Cheers,

 

Rob

http://www.willtheyfit.com/

:-)

Brilliant Dave thanks a mill.

 

LS108, thanks for the reply. The exact tyre size will be 225/45/18, the only difference being an increase in sidewall from 40 to 45 ..

 

Cheers,

 

Rob

Thanks LS108 ... Can the speedo be re-calibrated? I see it will show about a 3% drop ... This won't really bother me as all I want from this is better ride comfort and more protection for the wheels. If this won't work, I'll fit 17"  wheels with 225/45/17 tyres as I have on my MKI with no issues in 100,000 miles over the last three years.

 

Thanks again,

 

Rob

Just to add to that ... In my MKI the speedo reads 3% to 4% above actual speed. I know this because the tom tom sat nav I use shows the real speed. The MKI Edition came as standard with 225/45/17 although other models came with 16" wheels (not 100% sure of the tyre size though), so based on that the the MKII with a 45 sidewall may read actual speed correctly.

 

I await to be corrected.

 

Cheers,

 

Rob

I would not bother about 3%...

True, size isn't everything.

 

Thanks again,

 

Rob

Edited 14 February, 201412 yr by Robbo Cop

Just to be sure, I would doublecheck from the dealer if 225/45 r18 dimensions is ok and the tire won't touch anything in the suspension or so.

Thanks ... I already checked with a few people earlier today (main dealer and tyre supplier) and they say it shouldn't cause any problems like that. After all, the circumference of the wheel and tyre only increases by 22mm / 0.86614 inches.

 

Cheers mate,

 

Rob

Shouldn't really be an issue with such a small change but some insurance companies make an issue of fitting different size tyres to those originally fitted to the car (or recommended by the manufacturer).

Shouldn't really be an issue with such a small change but some insurance companies make an issue of fitting different size tyres to those originally fitted to the car (or recommended by the manufacturer).

I'm trying to sort that one, the broker was "not sure" on the phone so I'm going to email them and see what happens.If its a no I may fit good quality 205 55 16's. The stealers and some tyre people will only fit whats on the label. Around here all the tyre fitters laugh loudly when they see 40 18s arrive and suggest selling them to some boy racer for his GTI.. 

If i see the one with 225 50 17's around town I'll post a pic of it .

"Around here all the tyre fitters laugh loudly when they see 40 18s arrive and suggest selling them to some boy racer for his GTI.."

 

Interesting business model ...

 

 

Rob