Stock toyota D4D Vigo came with 265-65- 17 tires, wanting to put on a set 285 -70-17, can ir be done without lifting? Talked to dealer yesterday, and was told if I do a lift at all the warrantee is void. will I nee to lift to maount the 285 set.

diameter will increase by 2 inches approx, should be ok but beaware it will alter your speedo reading

found this

http://www.alloywheels.com/Tyre_Calculator

Quick ques, not trying to hijack...

Would the larger tires affect turning ratio/circumference? Is it the offset, the width or diameter that affects it?

You should put on 285 /60 X 17, that should give you the same circumference. Be sure the load value is the same too.

(Just in case: 285 is the width in mm, 60 is the ratio height/width and 17 the rim diameter in inch)

The 265/65x17 tyres on Vigo's do not look to have huge clearances at the front so going to a wider and higher profile tyre may not work. 2 inches diameter increase or 7% is a lot. Find someone with experience putting larger tyres on your truck who knows the limit for clearances or experiment if you can.

As dominique355 suggested, it is usually easier to go for a wider / lower profile size keeping the overall diameter similar. Increasing diameter 2 or 3% is usually feasible and speedos tend to under read that much anyway. It depends on your reasons for changing tyre size.

mr3cho, larger front tyres can reduce turn lock (or suspension travel) if they hit the inside rail or guards. The overall diameter and rim off set effect the clearances but the tyre width, profile and rim diameter determine the overall diameter so all factors contribute. Tyre cross section shape tends to get more square as the profile reduces which can also reduce clearence a little.