tyres - different size

Only in an emergency Luca.

As far as I'm aware, it is illegal to have two different tyre sizes on the same axle plane and besides anything else such as unmatched rotational travel due to different circumferences, the Insurance Companies would scrub you like an oily rag.

In an emergency, I would mix whatever I had available that fitted and to hell with anything else.

You probably end up with 'loppycoopers'.
Seriously i would only mix if i had no other choice re:- EMERGENCY!
Cheer's Bob.:)

Hi Luca,
If you have different size tyres on the same axle especially on an axle with an LSD, you will heat the diff up as one side will be turning faster than the other side. Over a long distance you may damage the diff. If you have different sizes front to back and engage 4wd on a fairly hard surface you can also wind up the transmission possibly causing somthing to break. If you need to use a different tyre place it on the front with the vehicle out of 4wd or the centre diff unlocked in a constant 4wd.
Hope that made sense
Tour Boy

Gidday mate
The 265 or 270 is the tyre width, the 75 or 65 is profile, the 16 is the rim diameter. I would not mix these tyres for the folowing reasons. Depending where you live, it is probably illeagal and your vechicle would be considered unroadworthy. The different profile will change the overall diameter and outside circumferance of the wheel/tyre. On the front the vechile may pull to one side, particually when braking, different tyre width may compound this problem. Damage could occur to front diff if driven in 4x4 or hubs locked in for long period of time.
If different tyre sizes on rear similar story, rear diff will contiually think you are going around a corner and diff cetre will turn, after long period of time potential diff wear or premature failure may occur. I would only consider different tyre sizes if I was out in the middle of the flat with minimal options.
Cheers
Steve

As mentioned previously, it's not desirable but will get you out of trouble. I've driven 75 series Cruisers on flats without drama apart from boiling power steering fluid, but it's not really what you'd describe as 'industry best practice'.

Do it right, do it once.

Did this to a late 90s jackeroo out west of Windorah to get him out of trouble.

He already had 3 flats, and only 2 spares.

So loaned him one of my 235/85/16 (32" OD same as a 265/75/16) for a couple of hundred K into Birdsville. Followed him in to make sure he got there, and to get the spare back.

His other wheels were 245/70/16 I think , and about 31" OD. Definitely looked smaller.

Don't know how much it wound up his rear LSD, but what the heck, it got him out of trouble.

Guys, thanks for the answers! I will put a new spare tyre on my truck!

Luca