Winter tyre sizes on standard alloys?

[ir_fuel]

Hi

 

I just checked with Bridgestone for wintertyres, to put on the (non rays) standard alloys.

 

I asked for 225/45/18 and 245/45/18

 

they got back to me and said that they dont have the rear tyre size, and that they verified and apparently a 235/50/18 also fits and they have that.

 

Now my question, is this ok? And secondly, arent the standard alloys themselves the same width front and back (rays are 8 and 8.5" if i am not mistaken), so maybe i can just put 225/45/18 at the back too??

 

help

[ir_fuel]

btw, i prefer to stick to bridgestones because i have a verrry good price on them

[lomoto]

std alloys are different widths front to rear

[Gus]

Nope,

 

Standard UK 18" alloys are both 8" wide, it was just the Rays that were different, ie 8 and 8.5

 

Gus

[lomoto]

Nope,

 

Standard UK 18" alloys are both 8" wide, it was just the Rays that were different, ie 8 and 8.5

 

Gus

yep your right...

[ir_fuel]

ok, so about the tyre size?

 

Anyone?

[Gus]

Depth of sidewall on 245/45 is 0.45 * 245mm = 110.25mm

 

depth of sidewall on 235/50 is 0.50 * 235mm = 117.50mm

 

Since there are two sections of tyre in the overall wheel diameter, then the 235/50 tyre diameter is 14.5mm too large

 

Would probably cause havoc with your ESP, etc

 

If you want to go to 50 section tyres, then should be 225/50, this would only be 4.5mm out.

 

HTH

 

Gus

 

ps 224/45 would be too small, ie sidewall is only 101.25mm

[ir_fuel]

And what about ESP/TC cutting in? I know its not supposed to work with wrong tyre sizes, but how does it react if you have a flat tyre and put one of those odd-sized "space-saver" wheels on temporarily? I had this on my TT and I cannot recall having had any TC problems whatsoever.