Offset needed

What offset do I need if I want to run 33/12.5 on a 2 1/5 in level?

 

Highly subjective but if you are interested in other people's rides the search function is your friend.

https://www.tundras.com/threads/gen-3-2022-wheels-and-tires-photo-thread.101215/
https://www.tundras.com/threads/offset.115593/#post-2975184
https://www.tundras.com/threads/suggestions-on-tires.115305/#post-2968131

 

Huh?

 

Offsets are a subjective thing. How much poke does he want? What type of tires is he running? Does he plan on using spacers? Is he taking off the mudflaps and felt? lotsa questions there.

 

Yup.

My reply was directed at the OP, as his question doesn't make any sense.

 

Interesting question…is that like a 275/95 or something…they make that?

You should probably go with 0 and lower to be sure to clear the UCA

 

His question makes sense - save the typo of 1/5 and the fact that more info needed but not necessarily required. Running a 33x12.5 requires more upper ball joint clearance, so you either need wheel spacers on stock wheels or less wheel offset to push the tire out more from the hub face and, in turn, the upper ball joint. Offset is referenced off of wheel centerline, not wheel edge. 0 offset means the wheel mounting surface is exactly in the middle of the wheel.

If you run an 11” wide tire with a stock 18x8 +60mm offset wheel, that means that the inside edge of the tire is 5.5” (half the tire width) plus 60mm (the amount the centerline of the rim has been pushed towards the outside of the wheel, which pushes the tire in towards the center of the vehicle) which is ~200mm. If you mount up a 12.5 wide tire, the inside edge of the tire is now moved half the tire widths difference inward, toward the upper balljoint. (12.5-11=1.5, 1.5/2=.75, .75”x25.4= 19mm) So the tire’s inner edge is now 219mm from the hub mounting surface.

In order to gain back the clearance you lost moving to a wider tire, you need to move the wheel out by subtracting the difference in backspacing. So you would get an 18x8 wheel with at most 41mm offset (219-200=19mm difference, +60mm factory offset -19mm = 41mm). But this only accounts for upper ball joint clearance, and not interference when turning. And the method applies to different whee widths, but not the exact numbers. If you are moving to. 9” wide wheel - which most aftermarket wheels are - you would need to subtract an additional 13 mm of offset (half of the difference between 8 and 9” wheel) to get the inner wheel edge to align with the factory offset. So take that 41mm new offset and subtract 13mm to get +28mm for a 9” wheel. Luckily, +27mm offset is pretty common in 18x9 wheels made for our truck. +19 is also popular.

If the need for a different offset confuses you, since - as mentioned above - offset is based off of wheel center, a wider wheel requires less offset to place the inner wheel edge in the same place as a narrower wheel. If, for example, you had a 8” whee is 60mm offset, the inner lip of the wheel is 203mm (8”) / 2 +60mm = 162mm from the hub mounting surface. A 9” wheel with the same offset would be 228/2 + 60 = 174mm from the mounting surface. That means the wheel edge is 12mm or roughly 1/2” further in, or 1/2 the difference between whee widths. This also means that a 9” wheel with +47mm offset would give the same wheel clearance on the inside lip as an 8” wheel with +60mm offset, but it would extend 1” or 25mm further outside the vehicle.

So, in short, you need a minimum of 19mm of additional clearance, or 19mm LESS offset, for a factory wheel width. Or 22mm LESS offset for an 9” wide wheel. 1.25” spacers on a factory wheel should be just about perfect, too, if you want keep your factory wheels.

33’s should clear a factory height suspension. 2.5” lift shouldn’t be an issue with the tire height - it’s the wheel width that can cause issues.