Diff ratio's

[Sith]

Hey all ,

My fender is running currently a 285x75x16 Cooper ST

Going by tire size charts the 285 is a 32 inch and the 255 is a 33 ... the orig rubber wear is a 235 which is a 31 inch ...
abait i find that these tires are crapola ... I would love the 255x85x16's so I will be getting some at a later date ... when these round black pieces of poo wear out ...they are 80%

So I want to concerntrate on getting the diff ratio's spot on .
Can you guys please point me in the right direction for quality , price , and where to get sorted !

thanx in advance

[long stroke]

Hey all ,

My fender is running currently a 285x75x16 Cooper ST

Going by tire size charts the 285 is a 32 inch and the 255 is a 33 ... the orig rubber wear is a 235 which is a 31 inch ...
abait i find that these tires are crapola ... I would love the 255x85x16's so I will be getting some at a later date ... when these round black pieces of poo wear out ...they are 80%

So I want to concerntrate on getting the diff ratio's spot on .
Can you guys please point me in the right direction for quality , price , and where to get sorted !

thanx in advance

285/75/16's are closer to 33"s, around about 32.8-32.9 inches and 255s are a propper 33 (maybe a tad over)
I wouldn't worry about diff ratio's on a defender with only 33's
They come standard with roughly 32's, so you are only increasing your tyre size by 1''
Different storry for a disco or rangie because they come standard with roughly 29's

CHEERS TIM.

[Sith]

Specification Sidewall Radius Diameter Circumference Revs/Mile Difference285/75-16 8.4in 16.4in 32.8in 103.1in 614 0.0%255/85-16 8.5in 16.5in 33.1in 103.9in 610 0.7%Specification Sidewall Radius Diameter Circumference Revs/Mile Difference235/85-16 7.9in 15.9in 31.7in 99.7in 636 0.0%255/85-16 8.5in 16.5in 33.1in 103.9in 610 4.2% is what I was looking at ....

[lambrover]

mate I am running 33's on my county and they are fine, the 255's are 33.3'' and you will be ok to run them, my speedo is still reading faster than actual speed I checked it against a gps so it's corrected it's self by about 4klms as with the standard tyres it was further out than that.

[isuzurover]

Specification Sidewall Radius Diameter Circumference Revs/Mile Difference285/75-16 8.4in 16.4in 32.8in 103.1in 614 0.0%255/85-16 8.5in 16.5in 33.1in 103.9in 610 0.7%Specification Sidewall Radius Diameter Circumference Revs/Mile Difference235/85-16 7.9in 15.9in 31.7in 99.7in 636 0.0%255/85-16 8.5in 16.5in 33.1in 103.9in 610 4.2% is what I was looking at ....

As your post shows:
235s ~ 32"
285s ~ 33"
255s ~ 33"

My 285s measured about 33.1" when new. My 255s about 33.3"

No change in gearing needed. You should also find that your speedo is spot on with that size tyre.