Diffs ratio

[Tom]

Hi
How could I know if the diff`s ratio is 4.88 or 5.29. I have a montero 2.5 TDI, with 4D56 engine? I`ve got 30x9.50 R15 tyres and I´d like to put bigger ones, 31 or 32".

[Bitsamissin]

Tom, how many revs does it pull at 100km/hr ?? I think it will pull about 3700rpm with standard size tires at 100km/hr with 5.29's or about 3300rpm with 4.88's.
Check for stickers on the front and or rear diffs which will show the ratio but they may have worn off by now.
Check with your local Mitsu dealer and give him the VIN no and he should be able to tell you the crownwheel & pinion part no's and or the ratio. If he can only tell you the part no's give them to me and I can find out.
Failing that remove the front diff cover and physically count the teeth on the crownwheel & pinion to work out the ratio.
37/8 = 4.625:1, 39/8 = 4.875:1, 37/7 = 5.285:1.

Frank.

[Tom]

Thanks Frank,
with 235 75 R15 the revs were about 3300rpm at 100 km/hr, so it should be 4.88. I'll ask mitsu dealer anyway.
Thank you and best regards from spain.