Why 225/45 and not 235/45

**lee gsi** · 26th December 2010, 21:33

Just been playing with a tyre size calculator and the 235/45/17 tyre is only 0.62% different to a 215/50/17 tyre.

But the tyre everyone recommends is the 225/45/17 which is 2.01% different.

At 70 mph:

225 tyre will be doing: 68.65 mph
235 tyre will be doing: 69.62 mph

**Big Sig** · 26th December 2010, 21:51

Because they look odd as they are a bit wide for the rim.

**diesel dog** · 26th December 2010, 21:57

235s may be acceptable depending on the distance between each rim (7J, 7.5J etc). I think that the 17 inch rims that Vectra's generally use as standard are only really wide apart enough for 225s. If the tyre is too wide for the rims it will tend to 'roll' too much onto its shoulders during cornering.

**lee gsi** · 26th December 2010, 22:06

Not sure what width my rims are.
Its to go on theses wheels:

**diesel dog** · 26th December 2010, 22:11

VX only recommend 225 max on standard 17 inch wheels.

**lee gsi** · 26th December 2010, 22:18

Ah thats a shame.

Would have been nice to get the extra rubber on the road and have the speedo more accurate

**diesel dog** · 26th December 2010, 22:26

Originally Posted by lee gsi

Ah thats a shame.

Would have been nice to get the extra rubber on the road and have the speedo more accurate

TBH I would rather have the speedo reading shown on the 225/45/17s than on the other extreme of 225/45/18s. At least then you definitely know you have a better chance of not being caught speeding.

**Big Sig** · 26th December 2010, 22:29

They will fit as netron had 235's, they just looked a bit silly.

Also unless you get it correctly calibrated your speedo isn't accurate anyway so its a bit pointless fitting them for that reason.