315 vs 265

[FNqGu04]

Hi Guys n Gals
As the title says, what's the difference between a 315/75/16 and a 265/75/16 .
ie difference in odometer,diameter ,etc
I know that it looks tough n all but I would like some better fuel economy and I think a smaller tyre will give me that .

Craig :feedback:

[MB]

G'day bloke, here's hoping this calculator found works mate.
https://tiresize.com/converter/
Your honest query has so many variables, big/small donk crank size etc....

[mudski]

Around town the smaller 265 or a 31 in the old scale would be better on the juice, whereas the 315 or a 35, would be better if your doing a heap of highway driving. But as MB has said, a lot of variables come into play.

[the evil twin]

When I used to run 35's I would use more fuel esp when towing. I had a set of 35 (Hankook) for tracks and a set of 33 (Bridgy) for towing/long haul touring but admit there are also other factors than just the tyre size.

Not sure how much difference there would be between 31 to 33 fuel useage but swapping from 35 to 33 was noticeable and if I went away I had to choose one or the other for the trip anyway.

What one should technically do if for whatever reason it is required to run larger tyres is change the diff ratio to return the vehicle to the same effective drive ratio.
The manuf will usually have the sorted out the most efficient drive ratio and changing tyre size either way will mean you give up something.
Rule of thumb for Patrols is one diff ratio for every two inches IE 31 to 33 tyres then 4.1 to 4.3 diffs or whatever (which is why those 4.6 diffs are so popular with the 35 inch tyre brigade)

Soooo...
If you are running taller tyres but haven't changed diff ratio and want your fuel economy back then that is what I would do otherwise, yes, smaller tyres will give you better fuel assuming the diffs are factory

[FNqGu04]

Thanks for the feedback guys.
I think I should start looking around for some new tyres ,I'm thinking of an A/T instead of muddies .
I have a friend who has a set of General Grabbers in an A/T on his Pajero ,any comments on these ?
Don't want to spend stupid amounts but not buy crap either,any suggestions ??

Craig