Quote:
Originally Posted by marconi118
for info I got 285 30 18 and 255 35 18 ad08r on my car
The 255 runs wide but the 285 runs narrow
if you put both side by side the 285 looks more a 265 compared to the 255
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Looks can be deceiving... but it depends on what the basis was for your measurements.
The following contains actual measurements taken on various wheel widths, not tyre manufacturers or resellers specifications, although, they're usually within a few millimetres (1/8") of each other. I prefer actual measurements as that is what I need to use to determine appropriate extreme wheel and tyre fitment on my car.
The section width for an AD08R 285/30/18 measures 288mm (11.34") on a 10" wheel, so it's not narrow. The measured rim for an AD08R 285/30/18 is 10".
The AD08R 285/30/18 on a narrower 9.5" wheel is 283mm.
The section width for an AD08R 265/35/18 measures 263mm, 270mm (10.63") and 278mm on a 9", 9.5" and 10" wheel, respectively. The measured rim for the AD08R 265/35 is 9.5". So the 265/35 on a 10" wheel is quite wide but it has a minuscule stretch since it's on a 10" wheel, which is the largest recommended wheel width for that 265 tyre.
When comparing the 265 and 285 on the same wheel, which I presume you did, there is a 10-13mm difference, which is relatively noticeable, which should be the case since one of the tyres being compared is being either stretched or pinched.
When comparing these two tyres on their measured rim, i.e. as they were designed, then there is a 18mm difference, which is certainly noticeable.
The section width for an AD08R 255/35/18 measures 259mm (10.20") and 265mm on a 9" and 9.5" wheel, respectively. The measured rim for the AD08R 255/35/18 is 9".
Again, an as-designed comparison of the 255, 265 and 285 on their respective measured rim shows a difference of 11mm (255-265), 18mm (265-285) and 29mm (255-285), which is a true reflection of the width differences, while a comparison between the three tyres on an in-common approved fitment 9.5" width wheel naturally shows a closer difference of 5mm (255-265), 13mm (265-285) and 18mm (255-285), due to the 255 being stretched and the 285 being pinched, but I don't think it's so little of a difference to say the 285 looks like a 265.
So these three AD08R tyres all run wide to different degrees, with the 265 fairing the best resulting in it being slightly closer to the 285, but it's still marginal at best.
So, as to whether the tyres look the same size, as I mentioned, it depends on what your metric is. I prefer using each tyre's specific measured rim or each tyre's specific measured rim + 0.5".