Hilux Revo 4x4 tires are 265/65R17. Can one replace these safely with 265/70R17 tires? Get different answers from different dealers.

Would not think that a one inch increase in tire diameter would make a big difference [65 to 70], because the tire width is the same [265].

The replacement tires I would like to get are not made in 265/65R17. Perhaps someone has done this tire diameter increase without problems?

Here is a table of equivalent sizes. Obviously if the tire diameter is less or more than the manufacturer specs the speedometer & odometer will no longer be correct.

https://tiresize.com/tiresizes/265-65R17.htm

This will calculate the compatibility.

http://www.blackcircles.com/general/tyre-size-calculator

The effect of larger diameter tyres on speedo accuracy is not usually a big problem as most speedos over estimate speed anyway.

Brake torque and clearance are the major issues.

265/70R17 are 3.4% larger diameter than 265/65R17. Oversize diameter by up to around 2% is usually regarded as OK and over 3% as risky, potentially effecting braking performance. The brakes can be checked if they still generate enough torque for the ABS to kick in at reasonable pedal pressure. Clearance with the extra 25mm diameter would also need to be checked. The OP might want to check if their insurance company has any issue as well.