37's on my 2024 zr2 bison 2500hd.

[sadZR2]

37 x 13.5 BFG KO2’s fit the HD ZR2 Bison perfectly with no issues.

I also fitted a 37 into the spare no issues with clearance. Super happy with the setup. I’ll report MPG difference after some 500 miles or so.

 

[AXE]

What's the clearance at full lock? It's tighter than just measuring when when the wheel is straight. That's where you'll likely rub, especially when your not in your driveway.

I see they mounted your rear bumper crooked too.

 

[sadZR2]

What's the clearance at full lock? It's tighter than just measuring when when the wheel is straight. That's where you'll likely rub, especially when your not in your driveway.

I see they mounted your rear bumper crooked too.

That’s a good point, I’ll check at full lock when I get back from Tahoe. I haven’t taken it on any off road tours yet but driving in the city and freeway so far zero issues.

 

[AXE]

That’s a good point, I’ll check at full lock when I get back from Tahoe. I haven’t taken it on any off road tours yet but driving in the city and freeway so far zero issues.

I think it'll be fine for normal road use. Probably won't rub unless you air down or off road hard enough.

 

[ghowell10]

These trucks look great with 37's. I'm new to the forum so if I'm missing another thread with the info I looking for please point me in the right direction. I do not have the Bison, so my question is, do 37's fit the normal ZR2 with the "stock" bumpers? I'm getting conflicting info from shops but they most likely have zero experience with the new ZR2 HD suspension. Bottom line is I'm going to wheel and tire my ZR2 but want to be completely sure 37x12.50's will fit before pulling the trigger. Thanks in advance for any and all info.

 

[AXE]

These trucks look great with 37's. I'm new to the forum so if I'm missing another thread with the info I looking for please point me in the right direction. I do not have the Bison, so my question is, do 37's fit the normal ZR2 with the "stock" bumpers? I'm getting conflicting info from shops but they most likely have zero experience with the new ZR2 HD suspension. Bottom line is I'm going to wheel and tire my ZR2 but want to be completely sure 37x12.50's will fit before pulling the trigger. Thanks in advance for any and all info.

Just mount one up and see, thats what I did. Got a detailed post showing the results. That's the only way you'll know cause every tire is different.

There's a lot of clearance in wheel wells, so the limiting factor is stock wheel + offset. You don't have a lot of clearance between UCAs with stock tires. You'll have much less with 37s.

In my opinion, you need 0 or negative offset wheels to get clerance on UCAs if your gonna run hard off road or air down. Negative offset wheels will potentially cause clearance issues in wheel wells, becsuse at full lock they are now closer to the body and bumper.

 

[AXE]

37 x 13.5 BFG KO2’s fit the HD ZR2 Bison perfectly with no issues.

I also fitted a 37 into the spare no issues with clearance. Super happy with the setup. I’ll report MPG difference after some 500 miles or so.

Your passenger side rear bumper isn't square with the quarter panel. It's a feature, not a flaw.

 

[sadZR2]

I think it'll be fine for normal road use. Probably won't rub unless you air down or off road hard enough.

After some driving around there is a very minor rub in the front. It’ll just tap the frame at full lock.

I’m still waiting for the Bora Spacers. Should solve that

Fuel Mileage seems to be the same as well. I haven’t had the tire size calibrated quite yet.

 

[Epsilon Plus]

The only rub I have with is a hair on the fender liner when backing up. No touch on metal. Sway bar is tight but no rub. UCA has room for days. 37x12.5 Nitto Recon Grapplers on a GM 18x8 wheel unknown offset. I think I can heat up the liner and press it back and it will give me what I need. UCA ball joint angle is perfect leveled to the rear. I would not be surprised the engineers designed the suspension changes to allow 37s. Full disclosure I have a 22 LT truck that I swapped all the ZR2 part numbers into. If my truck can fit them, stock ZR2s will have no trouble either.

 

[CaptCUNextTues]

I would love 37’s, and they would look awesome on this truck, but I just got 22.8mpg(unloaded)on a 400 mile trip(cruise set to 5-8 above speed limit(65avg)). I then grabbed our crappiest/heaviest 2 horse steel frame trailer, and towed it to a horse show, another 400 miles, did 16mpg. I have 15k on this truck currently, and my mpg has only improved. If I was going to create a project truck with similar trim, I would grab a base LTZ. I think GM did more homework than normal on our ZR2’s, definitely not perfect, but I am really hesitant about upsetting what seems to be a very well thought out compromise. I also spend a good portion of my time on sand, 25psi works fine on the stock tires, as usual, Axe is probably right on clearance

 

[AXE]

I would love 37’s, and they would look awesome on this truck, but I just got 22.8mpg(unloaded)on a 400 mile trip(cruise set to 5-8 above speed limit(65avg)). I then grabbed our crappiest/heaviest 2 horse steel frame trailer, and towed it to a horse show, another 400 miles, did 16mpg. I have 15k on this truck currently, and my mpg has only improved. If I was going to create a project truck with similar trim, I would grab a base LTZ. I think GM did more homework than normal on our ZR2’s, definitely not perfect, but I am really hesitant about upsetting what seems to be a very well thought out compromise. I also spend a good portion of my time on sand, 25psi works fine on the stock tires, as usual, Axe is probably right on clearance

That's some damn good mileage. I haven't even put 1800 miles on mine and it's damn near 6 months old. I gotta get some trips in soon. Still want to do 37s on different rims. But if I do, I'll keep my stockers for longer trips.

 

[CaptCUNextTues]

That's some damn good mileage. I haven't even put 1800 miles on mine and it's damn near 6 months old. I gotta get some trips in soon. Still want to do 37s on different rims. But if I do, I'll keep my stockers for longer trips.

Please note the best mileage was between Fenwick Island, DE and Richmond, VA, as flat as you get besides driving across North Dakota. Mileage also jumps with the temperature, lower wind resistance. Temperature was around 55.

 

[AXE]

Please note the best mileage was between Fenwick Island, DE and Richmond, VA, as flat as you get besides driving across North Dakota. Mileage also jumps with the temperature, lower wind resistance. Temperature was around 55.

Yeah, out west we have some long flat stretches in some areas, but lots of hills and mountains to screw things up. But that's better mileage than I've seen on my previous lifted trucks. I know guys with standard HDs said they could get 20-22 mpg. I think the best I've ever seen was between 18-19 mpg and that was rare.

 

[CaptCUNextTues]

It will definitely be hard to replicate, anyone who has done rt 13 and the bridge tunnel on the eastern shore knows about the 50-45 mph zones/stop lights. I did it in the evening.

 

[AXE]

I just pulled my best mileage yet at 19 mpg. It was about 20% city streets in traffic, about 40% Parkway at steady 55 mph, 40% freeway steady at 75 mph. This is pretty damn good.

 

[robertszr2]

Just got these nitto 37's installed and so far I can not make them rub in any circumstance! Truck looks so much better now. This is how the truck should of came!!! I did 1 full turn on the front torsion bar just for extra insurance but they didn't rub even before that.View attachment 10189View attachment 10190View attachment 10191View attachment 10193

How did this affect performance, towing, fuel economy, and overall ride in comparison to stock 35" Considering doing the same with BFG KO

 

[CaptCUNextTues]

What's the clearance at full lock? It's tighter than just measuring when when the wheel is straight. That's where you'll likely rub, especially when your not in your driveway.

I see they mounted your rear bumper crooked too.

Mounted my front bumper crooked, Friday’s……

 

[CaptCUNextTues]

I just pulled my best mileage yet at 19 mpg. It was about 20% city streets in traffic, about 40% Parkway at steady 55 mph, 40% freeway steady at 75 mph. This is pretty damn good.

Sounds about right, my magnificent 23mpg was straight highway, flat, middle of the night, and maybe 4 rolling stoplights. 400 miles round trip to Richmond, VA and back. I am guessing less than 1000lbs over vehicle weight, average 65mph.

 

[robertszr2]

Yea your tires are 14.2 inches wide when inflated to spec. I'm actually surprised its not rubbing right now.

Did you also do a 37" spare?

I'm installing some BFG KO2's 37x13.5 on Thursday. Overall width is supposed to be 12.8 I will report back about fitment. I wouldn't mind running a BORA 3/8 spacer worst case scenario.

The only reason I picked BFG KO2's was due to Triple Peak Snow Rating. We are planning a trip to tahoe and figured it's a good enough reason for a forced upgrade.

Did you get the KO2....did it fit?

 

[BlackBisonAMG]

Great info , gents. Thanks for the insight.

We are picking up our ZR2 HD DMax on the 9th, then moving back out to Montana from Florida. A 3 Peak tire is a must for us. I've heard a lot of great things about the new Goodyear Boulder MT's (link here). Ill drive the truck out on there OE's but will switch them out for the Boulder MT's once we are settled. They don't offer a the 37's in an 18" wheel option or 13.50" wide option for the 20" wheel. So, 37x12.50r20 is what I'll go with. Ive had the Falken WP AT3W's in the past and loved them but these Goodyears seem to be some of the best 3 peak tires from what I've heard across multiple forums.

Has anyone aired down or articulated the suspension to find any rub points on the non-Bison ZR2 with 37x12.50's? As @AXE mentioned the 0 to -12mm offset will help but I don't want to go with more of a negative offset than I have to.

Thanks for the help.