I need gear ratio and tire help

[GM Rat]

I'm new to this forum. Here is what I have..... I just purchased a 2019 Silverado 1500 (old body style) 4X4 with 14,000 miles on it. It has the 6 speed trans with a V8 5.3 with a 3.42 rear end and stock tires (265/65/r18). I had a 2 inch leveling kit put in the front.  With a tonneau cover I'm getting 24 mpg highway and 22 mpg city.  I just ordered $3200.00 in rims and 35 inch tires for no other reason than the coolness look. The rim manufacture said the new 18 inch rims and 35 inch tires would fit. The stock rims have a 26mm offset and the new rims have a 18mm offset. So....... after I ordered my rims and 35 inch tires It came to my attention that I should change my gearing from a 3.42 to maybe a 4.11. Thats another $2,000 there abouts, I dont want to deal with that at this time. So I called the tire shop and cancelled my 35 inch tires and will put my new rims on my stock tires. Now I'm wondering  if I can keep my 3.42 rear end and put 33 inch tires on. I've been reading so much the last few days it is making my head spin. How much bigger in tire size can I go if any and keep my 3.42 rear end? Dont forget I have the 6 speed trans with a 2 inch leveling kit in the front. Can anyone point me in the right direction? 

 

Thanks

GM Rat

Edited July 7, 2022 by GM Rat

[CamGTP]

The 33's with stock gearing will be fine. The stock 20's are damn near a 33in tire depending on which tire it comes with. You will be saving a ton of weight going with 33's over 35's and won't take a huge hit to fuel mileage like those 35's would.

 

Just know that your speedo will still be off some with the 33's unless you get it tuned or buy one of those speedo calibrators to fix it.

[Gangly]

To go from a 31.7" tire to 35" tires, you would need to go from the factory 3.42's to 3.79's, or basically a 3.73 gear assuming tire and wheel weight combination stays somewhat the same.  A difference for sure, but not a staggering difference and I would personally have to think long and hard about whether it would be worth it.

 

Going from 31.7" to 33" would require a gear swap from your stock 3.42's to 3.56's to maintain identical performance.  Its not worth it to swap gears as there would be minimal gains felt, especially if utilizing near factory weights for your wheel and tire combo.

[Spurshot]

I can tell you my experience in going from a stock 32" street type pattern tread to a much wider 33" hybrid off-road type aggressive  tread.  My 14 1500 CC was getting about 19mpg hwy and the tire change alone dropped it to 15.5mpg. 

Edited July 7, 2022 by Spurshot

[GM Rat]

Thanks everyone for the reply. I think I will stay with stock tires and put my new rims on
them. These are called  Dirty Harry. Can you see the revolver, lol