ZR2 Oversize Tires Thread

[PBSlinger]

Yep, advertised "spec" sheet sizing doesn't always equal true installed size. I've even seen inconsistencies comparing same exact tire brand/model/size from one build date to the next.

 

[AXE]

Also ride height is affected by wheel width too. If your on stock 8.5 inch rims, I would expect them to ride a tad higher versus an aftermarket wider 9-9.5 inch wheel.

 

[Keewatin427]

Tire size (315/70R17) Mickey Thompson Baja Boss
Wheel (Method 312 17” -12 offset)
Suspension modifications
Any trimming performed (Dirt King upper control arms. Peak 1.5 inch front lift)
I needed to trim the front bumper by 2 cm and add several washers to space out the front bumper. I trimmed the plastic inner fender liner closest to the firewall and removed the bolted on crash spacers.

 

[GATORB8]

Yep, advertised "spec" sheet sizing doesn't always equal true installed size. I've even seen inconsistencies comparing same exact tire brand/model/size from one build date to the next.

100%, the brand trends in inflation sizes tend to follow a “similiar” tolerance. The 37” BFG KO2s on our Jeep are 100% smaller than the 37” Nittos Ridge Grapplers on the ZR2. Just like our old 35” KO2s were smaller than my 295/65R20 Nittos (35” sidewall stamp).

Not talking enough to change sizes you choose by brand (a 37” BFG isn’t as small as a 35” nitto), but makes a huge difference in confirmed clearance.

Make sure you match offset on an example as well. Wheel width does impact section width, so if you are going off reservation, you’ll want to adjust for UCA clearance based on the “measured wheel width”

 

[PBSlinger]

Truck: 2024 Silverado 1500 zr2 Bison
Tire: Cooper Discoverer Stronghold at
Tire size: 285/75r17
Wheel: Method 703, 17x8.5 et0
Suspension modifications: None
Any trimming performed: None
No rubbing full lock both ways

Alright so as I figured when switching from the 295/70r17s the Coopers run slightly undersized compared to others. Really glad I switched to the 285/75r17s as they are the perfect size for this tire and truck. Completely stock suspension and zero trimming I’m getting no rubbing full lock both ways, including full lock in reverse.

Will try to get more pics later, this is the cleanest these tires will ever be lol.

 

[AXE]

Truck: 2024 Silverado 1500 zr2 Bison
Tire: Cooper Discoverer Stronghold at
Tire size: 285/75r17
Wheel: Method 703, 17x8.5 et0
Suspension modifications: None
Any trimming performed: None
No rubbing full lock both ways

Alright so as I figured when switching from the 295/70r17s the Coopers run slightly undersized compared to others. Really glad I switched to the 285/75r17s as they are the perfect size for this tire and truck. Completely stock suspension and zero trimming I’m getting no rubbing full lock both ways, including full lock in reverse.

Will try to get more pics later, this is the cleanest these tires will ever be lol.

View attachment 17310View attachment 17311View attachment 17312

285s always looked good on non lifted 1500s.

 

[Leonidas]

Truck: 2024 Silverado 1500 zr2 Bison
Tire: Cooper Discoverer Stronghold at
Tire size: 285/75r17
Wheel: Method 703, 17x8.5 et0
Suspension modifications: None
Any trimming performed: None
No rubbing full lock both ways

Alright so as I figured when switching from the 295/70r17s the Coopers run slightly undersized compared to others. Really glad I switched to the 285/75r17s as they are the perfect size for this tire and truck. Completely stock suspension and zero trimming I’m getting no rubbing full lock both ways, including full lock in reverse.

Will try to get more pics later, this is the cleanest these tires will ever be lol.

View attachment 17310View attachment 17311View attachment 17312

I think the Bison AEV bumper has quite a bit more clearance than the stock bumper

 

[wutang61]

295/70R18 KO3’s
Stock wheels 3/8” spacers (effective +18 offset.)
No hard clearance issues at all in roughly 1000 miles. They just brush the inboard fender liner fabric on full crank.

I’m comfortable in saying this is absolutely as far as you can push a stock suspension truck without modifying anything.

Tires are absolutely fantastic with 45/42 pressure. Highly recommended.

 

[The_Q]

295/70R18 KO3’s
Stock wheels 3/8” spacers (effective +18 offset.)
No hard clearance issues at all in roughly 1000 miles. They just brush the inboard fender liner fabric on full crank.

I’m comfortable in saying this is absolutely as far as you can push a stock suspension truck without modifying anything.

Tires are absolutely fantastic with 45/42 pressure. Highly recommended.


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Just curious, are you using extended thread lug nuts with the 3/8” spacers? Or are you just using the stock lug nuts?

 

[wutang61]

Just curious, are you using extended thread lug nuts with the 3/8” spacers? Or are you just using the stock lug nuts?

The Spacers are hub centric and use the stock studs. Plenty of engagement on the threads. No concern of a wheel falling off. Anything more than 3/8 or 10mm you will need to extend the studs.

 

[The_Q]

The Spacers are hub centric and use the stock studs. Plenty of engagement on the threads. No concern of a wheel falling off. Anything more than 3/8 or 10mm you will need to extend the studs.

Thanks! I have those spacers. I also bought extended thread lug nuts, but I don’t like the size of the nut itself. Guess I’ll give it a try with the stock lug nuts.

 

[LSnTX]

@wutang61 that looks good,
Do the 295s require the higher pressure?

 

[wutang61]

@wutang61 that looks good,
Do the 295s require the higher pressure?

LT tires require a higher pressure vs P metrics for the same load rating. More belts so the tire is resistant to expansion.

When I ran anything lower, I could feel the tires acting out of balance. Vibration was noticeable until they heated up and pressure rose to 42+. Truck felt loose in its shoes so to speak.

 

[Nmass94]

295/70R18 KO3’s
Stock wheels 3/8” spacers (effective +18 offset.)
No hard clearance issues at all in roughly 1000 miles. They just brush the inboard fender liner fabric on full crank.

I’m comfortable in saying this is absolutely as far as you can push a stock suspension truck without modifying anything.

Tires are absolutely fantastic with 45/42 pressure. Highly recommended.


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Looks great- do you think the spacers were necessary for fitment? Any scrub offroading?

 

[Waterdog]

@wutang61, how do you like the ko3’s? They get very mixed reviews. I had a set of ko2’s on my 4Runner years ago and was amazed how quiet they were considering the tread pattern

 

[GATORB8]

LT tires require a higher pressure vs P metrics for the same load rating. More belts so the tire is resistant to expansion.

When I ran anything lower, I could feel the tires acting out of balance. Vibration was noticeable until they heated up and pressure rose to 42+. Truck felt loose in its shoes so to speak.

Tiresize.com has a really nice calculator that will modify the door sticker PSI to match the tire load capacity when you change tire size and load rating.

Tire Pressure Calculator

Easy to use tire pressure calculator. Use our tire pressure calculator to calculate the new tire pressure needed when changing tire sizes.

tiresize.com

My rears for example:

 

[wutang61]

Looks great- do you think the spacers were necessary for fitment? Any scrub offroading?

Not at all required for fitment. Purely an aesthetic choice.

I haven’t done anything hardcore off-road but it has not touched thus far. Without spacers there’s absolutely zero chance of them rubbing. But these tires are 34.3”. Be mindful of whatever your choice measures out to as there can be variance. Mickey Thompsons for example measure 34.5 and I can’t vouch for that.

 

[wutang61]

Tiresize.com has a really nice calculator that will modify the door sticker PSI to match the tire load capacity when you change tire size and load rating.

Tire Pressure Calculator

Easy to use tire pressure calculator. Use our tire pressure calculator to calculate the new tire pressure needed when changing tire sizes.

tiresize.com

My rears for example:

View attachment 18010

Going off that calculator for the factory C rated Goodyears they claim 35 psi. The tires are mashed potatoes at that pressure. Much too low.

I originally started based on that calculation. Way off. BFG stands hard on 45psi bare minimum operating pressure(for street use). My tires warm will run 49-50 front 45-46 rear.

 

[wutang61]

@wutang61, how do you like the ko3’s? They get very mixed reviews. I had a set of ko2’s on my 4Runner years ago and was amazed how quiet they were considering the tread pattern

Honestly coming from the stock tires @20k miles, it’s unbelievable. The radio is usable at volume levels below 50% now and I can actually hear other vehicles tire noise as they pass me. Normal conversations can be had and I can actually hear the Corsa Exhaust.

From stock they are dead quiet.

 

[DNZR2]

Going off that calculator for the factory C rated Goodyears they claim 35 psi. The tires are mashed potatoes at that pressure. Much too low.

I originally started based on that calculation. Way off. BFG stands hard on 45psi bare minimum operating pressure(for street use). My tires warm will run 49-50 front 45-46 rear.

FWIW the placard on my 2022 said 35 psi while the placard on my new 2025 says 38 psi.