Any harm in changing from 215/40 R17 to 215/45 R17?

[Generic]

My exisitng tyres are verging on illegal, and being winter soon I figured I'd get all four corners onto winter tyres. I can't really find much for 215/40 R17 (my current tyre's rating), but there's quite a few tyres available for the slightly larger profile size at 215/45 R17.

Would my Ibiza FR 2.0 TDi be OK with these? It's about 3.5% difference in diameter (about 2cm). It looks like there should be loads of room to accomodate an extra 2cm, but I just thought I'd ask to be sure?

 

[DEAN0]

My exisitng tyres are verging on illegal, and being winter soon I figured I'd get all four corners onto winter tyres. I can't really find much for 215/40 R17 (my current tyre's rating), but there's quite a few tyres available for the slightly larger profile size at 215/45 R17.

Would my Ibiza FR 2.0 TDi be OK with these? It's about 3.5% difference in diameter (about 2cm). It looks like there should be loads of room to accomodate an extra 2cm, but I just thought I'd ask to be sure?

Probably better on 205/45-17 - they are only 2% different and the slightly narrower tyres would be better in the snow.

Just be careful because you will now be travelling faster for each speedo reading so you will have less tolerance before tickets arrive if you sit on the speed limits passed cameras.

Also check with your insurance - it will be classed as a modification from standard

 

[Generic]

Probably better on 205/45-17 - they are only 2% different and the slightly narrower tyres would be better in the snow.

Just be careful because you will now be travelling faster for each speedo reading so you will have less tolerance before tickets arrive if you sit on the speed limits passed cameras.

Also check with your insurance - it will be classed as a modification from standard

Surely if the wheels are bigger, won't speedo will read higher? I.e. if I'm driving at 60mph currenly, when I change a 45% profile, then travelling at 60 will actually be in the fifties?

 

[DEAN0]

Surely if the wheels are bigger, won't speedo will read higher? I.e. if I'm driving at 60mph currenly, when I change a 45% profile, then travelling at 60 will actually be in the fifties?

NO - the bigger tyres will take you further for each revolution.

So for a wheel turning the same speed - a 215/45-17 will take you 3.5% further than the standard 215/40-17

The speedo will only count the revolutions of the wheel to show a speed.

 

[Generic]

NO - the bigger tyres will take you further for each revolution.

So for a wheel turning the same speed - a 215/45-17 will take you 3.5% further than the standard 215/40-17

The speedo will only count the revolutions of the wheel to show a speed.

Oh yeah, sorry. When I checked here I put the sizes in backwards. Is there a way to recalibrate the speedo?

 

[NetworkMan]

I agree with DEANO. According to my calculations about 3.6% difference. You also have to consider that the tyre width may not be optimum for the rim width. It depends on the rim width and I don't know that.

 

[csd_19]

Your speedo will become more accurate, if you do go for the 45 profile tyres check your speed on GPS before and after fitting

 

[DEAN0]

Your speedo will become more accurate, if you do go for the 45 profile tyres check your speed on GPS before and after fitting

I thought that at first - but my FR TDi speedo and my GPS are pretty close all the way up to about 110 ( checked over a good distance on the German autobahns )

That's why I pointed out the possible issue with cameras.