Somebody check my math. v. Wheel calculations

[RedRocket1647545505]

Ok, here goes:

 

Subject: 2007 Chevy Colorado Xtreme

 

Question 1 Part A:

 

Stock wheel specs:

-Diameter = 18"

-Width = 8"

-Offset = +28mm

-Bolt pattern = 6 x 5.5"

 

New wheel specs:

-Diameter = 20"

-Width = 8.5"

-Offset = *to be determined*

-Bolt pattern = 5 x ? (neogotiable)

 

Switching wheels will require the use of a bolt pattern adapter.

 

Adapter specs:

-Width = 1.900" (48mm) MINIMUM

-Bolt pattern = 6 x 5.5" --- 5 x ? (whatever I choose)

 

 

Now, in order to avoid any clearance issues, I'd like to keep the offset of the new wheels, as well as the overall external dimensions of the tire (plus sizing?), as close as possible to stock specs.

 

Here's the rundown:

 

Essentially, if I run a 48mm adapter plate behind the wheel, it will give me 48mm LESS (towards the negative) offset than what I'm currently running (+28mm). Doing so would put me at a -20mm offset. Not where I want to be. So, in order to counteract that, I would basically need to purchase a set of wheels with a +48mm offset.

 

Is this correct logic?

 

+28mm (stock offset) - 48mm (adapter) = -20mm (total offset)

 

-20mm (total offset) + wheel with +48mm offset = original +28mm offset

 

Amirite so far?

 

If so, move on to part B of the question.

 

Question 1 Part B:

 

Here are my BEST options as far as what available for the wheel I want:

 

Bolt Pattern / Offset

 

-5x108mm (4.25") / +42mm

-5x120mm (4.75") (my first choice in bolt patterns) / +20mm

-5x120mm (4.75") / +35mm

 

 

Now, according to my math in part one, I would need a wheel with as close to +48mm offset as possible to stay as close to my stock geometry as possible.

 

That would obviously be the first choice. Though, it would still put me 6mm short of my goal. What this mean is the wheels would be moved out 1/4" further on each side, not counting the additonal 1/4" caused by the extra wheel width. But, in the end I would prefer to go with the 120mm spacing if at all possible.

 

If I went with the 120mm option, the +35mm would be the clear choice in that regard. However, it would put me 13mm (1/2") short of my goal.

 

13mm short of my goal = the wheels would stick out 1/2" further on each side. 3/4" when you factor in the wheel width as well.

 

 

Which wheel do I go with?

 

 

p.s. Truck will be left at stock height. I have also yet to check how much clearance I have with the stock tires/wheels. Doing so would greatly help me answer this question. Until then, all I've got is CR's advice.

 

[Guest GMoney]

I would go with option three, it will look better.

 

Why can't you find any wheels that have the proper bolt pattern?

[RedRocket1647545505]

I would go with option three, it will look better.

 

Why can't you find any wheels that have the proper bolt pattern?

 

The particular wheel I want isn't offered in 6 bolt.