darkside said:
225 65 18 should be the same diameter plus or minus 1 or 2 %
A 225/65x18 = 225mm width, x 65% sidewall aspect, plus 18" rim.
225 x .65 = 146.25mm sidewall height.
146.25mm sidewall + 18" rim (457.2mm) + 146.25mm sidewall.
146.25mm + 457.20mm + 146.25mm = Total height of 749.7mm, OR
29.51" tall.
The oem 235/50 = 117.5mm sidewall aspect, giving a total tire/wheel height of 692.2mm, or
27.25" total height.
Total difference is 2.26" all together, which is about a 9% difference.
That being said: Tires can vary by 7% larger or smaller, of the same printed size, based on manufacturer. Check with the specific manufacturer for tire size, based on the MFGer's specs.