Rav 4.2 different front - rear AT tires?

[ekklesis]

Hello all,

I have a 2005 R4.2 D4.D 4WD and recently I got two General Grabber AT2 225 75R16 used tires. I'm wondering if for these type of transmission I really need identical thread pattern both front and rear or I can use other tires on one axle?

 

 

 

 

 

 

 

 

 

[IanML]

I would advise against, because the 4WD system relies on front and rear having the same diameter, and comparing rotation between front and rear.  A discrepancy could affect the system.

[roadster-rav]

This comes down to whether the rolling circumferences match within the tolerances that would be expected allowing for different pressures and temperatures that could occur front to rear. If you wanted to experiment you could find a flat and quiet stretch of road, mark a point on each tyre at the bottom of each wheel as it stood, then run slowly in a straight line for a short distance, then observe the relative positions of your marks. If they all correspond then the rolling geometry is probably OK. This would be better done with original and then changed tyres to get some idea of the allowable variation. I suspect if electronics are involved there is probably some kind of self calibration to allow for differences in wear and inflation pressures anyway.

[IanML]

I understand the 4.2 4WD system is purely mechanical - no electronics involved.

[ekklesis]

Yep like Ian says, the transmission is indeed purely mechanical for the second generation with a viscous coupling transferbox / diff so I believe that there shouldn't be any problems like the ones with systems based on the ABS sensors input.

In fact now I have mounted (just temporary) General Grabbers AT2 225 75R16 and the ones on the back are much more used up than on the front and I haven't felt anything suspicious.

Soon I'll go with a new set of Cooper Discoverer AT 225 70R16 because I've heard great things especially from tacomaworld forums.