Modern OEM wheels on Older Truck…Need Insight.

[KennyP]

(I hope this is posted in the correct spot. If not can a Moderator please move it to the correct location)

Truck:
1988 k1500 Silverado 5.7L
94k miles
Goodyear Trail Runner AT - LT285/75/16
Completely stock, down to the pancake catalytic converter. (Which will be swapped soon)

TLDR - Want modern wheels..flat tire decreased decision timeframe..currently stock wheels, modern wheels have positive 26 offset. Will that cause problems with tires rubbing on body-suspension-brake lines? Any information would be greatly appreciated.



A Little Background; A month ago I was “Sunday driving” up in the mountains when I had a flat tire. Not repairable, sucker just shredded. Date code on these tires Are (18/18) so naturally it’s time to get new ones. I knew that as I noticed dry rot starting to form between the treads as well as a small amount where the sidewall meets the tread during a wash before the trip. The truck isn’t a daily driver and the driver side gets beaten by the So Cal Desert Sun.(in hindsight I should’ve rotated them much more often) I’m sure they have a smidge less than 10k miles but it is what it is. New tires are on the horizon but there will be upgrades to brakes and suspension. No “lift” just steering, ball joints, control arms and whatnot. This was my grandfather‘s truck, after he passed it became mine. I believe if you have it use it… when it sits, it rots away. That’s when small problems become big problems. Just like separating a tread in the mountains only to learn your spare tire has a date year of 2012, is low on pressure from a leaking valve stem and riddled with dry-rot it’ll give the Grand Canyon a run for its money.

Dilemma;
I’d like this thing to stop and handle better. Along with suspension components I’m thinking Larger front rotors and disc brakes in the rear. Naturally I figured I would need something larger than a 16 inch rim. I enjoy getting out into the wilderness and camping so 18 inch wheels are the largest I’m going to go. It should give me more than enough space to fit larger rotors. (that’s the idea, not sure if it will work without an experience level that is vastly superior to mine) So for a while now, I’ve been looking at larger wheels, specifically Trail Boss wheels. I just really like the way they look.

Question -need insight here; Is there any advice anyone can give a guy looking to put newer model wheels on our older trucks?
Things like;
-Any scrubbing of bodywork when full lock
-Clearance issues
- if it’s a 4x4 are there any suspension/Brake components that show signs of rubbing.

I’m currently running the factory steelies which I believe are a 0’ offset (or close to it, not sure because I can’t find any info on 30+yr old wheel specs) and these new wheels I have my eye on have a positive offset of 26.
Now I’ll admit I’m clueless about that offset/Backspace stuff and I am struggling to wrap my head around it. All I really know is the farther out your tires stick out the more stress you put on your components like bearings and ball joints which correlates to negative offset. On the other hand, positive offset means your tire is tucked in the wheel well more. (I might have that ass backwards)
I really like the trail boss wheels and was close to pulling the trigger until I came across these other wheels. So I crudely used a browser photoshop and made a comparison of what the truck will look like with the tires and running boards removed. (Will be “customizing” Amp Research Power Steps to fit)
keep in mind for my truck, white lettering is a Must.

*New Tire Size will be 265/65/18 if that changes anything.

Thank you for taking the time to read my story and thanks for the feedback(totally optional)

Uploads will be what kicked off this thread. The current version of the truck and the photoshopped side by side version. Then one because I feel like the color combos just mesh.

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[89RCLB]

Very nice looking truck!

I've ran these wheels on both of my K1500's without issue, they're from a 2012 Z71 Suburban.

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Your stock wheels are 16X6.5 with an offset of 49mm (couldn't find center bore measurement but didn't look real hard either). These wheels on my K1500 are 18X8 with an offset of 31mm and the center bore is 78mm. No rubbing/interference issues whatsoever.

I would double check the specs of the wheel that you're looking to use on your truck but I would venture that you won't have any problems, I've seen many trucks with the newer OEM wheels on them.

Good luck!

 

[Schurkey]

1988 k1500 Silverado 5.7L

Regular-cab truck. Almost certainly JN3 brakes--the worst/weakest power brakes ever fitted to a GMT400-series truck.

there will be upgrades to brakes and suspension. No “lift” just steering, ball joints, control arms and whatnot... ...Along with suspension components I’m thinking Larger front rotors

Find an extended-cab, or a newer GMT400 with JN5/JB5, or JN/JB6 brakes. Grab the power booster, master cylinder, calipers, rotors, and hubs if not the entire steering knuckle.

Up front, the JN/JB5 and JN/JB6 brakes are the same, and much better than JN3.

In back, the JN/JB5 brakes suck exactly as much as the JN3. JN/JB6 rear brakes are MUCH better.

and disc brakes in the rear.

Probably a mistake unless you're using GM parts from a newer truck with a GVWR AT LEAST as high as what you have now.

If you have dreams of some aftermarket disc brake downgrade, think again. Takes REAL money to get a decent aftermarket rear disc conversion. There's heaps of crappy aftermarket rear disc conversions from multiple zero-engineering, rip-off artists companies, though.

Naturally I figured I would need something larger than a 16 inch rim.

Need? No. Want? Maybe.

18 inch wheels are the largest I’m going to go. It should give me more than enough space to fit larger rotors.

Larger-diameter rotors means you need to space the caliper farther from the wheel center. Which means different steering knuckle, or some sort of kludged-up adapter brackets.

Good luck.

OTOH, calipers with bigger pistons would provide more force on the brake pads, AND you keep the existing steering knuckle, AND you can source JN/JB5 or 6 cores in the Treasure Yard for minimal investment.

When it was me, I took EVERYTHING except the rear axle from my JB5 extended-cab donor truck--booster, master cylinder, rotors, hubs, calipers.

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The rear axle came from a different donor.

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I can't help with wheels.

I can tell you that the single-best "brake" upgrade you can make is to throw the 254mm (10") leading-trailing shoe rear drum system in the scrapmetal bin, and upgrade the rears to the 11.x Duo-Servo brakes. This is even more important than upgrading the front brakes/booster/master cylinder as described above. (Of course, you could do both ends. I did.)

The BEST way to upgrade to the 11.x rear brakes is to scrap the entire rear axle in favor of a 6-lug, K2500 9.5" ring gear, semi-float axle of the proper gear ratio. Choose your core wisely, don't buy one that's got gear/bearing/brake problems, and make sure you get the U-bolt plates that go with the K2500 axle. You'll need a 447 conversion U-joint for the driveshaft, new U-bolts and nuts, and whatever repair parts the axle/brakes need to be serviceable, including park-brake cables if the ones on your truck are seized.

 

[KennyP]

Very nice looking truck!

I've ran these wheels on both of my K1500's without issue, they're from a 2012 Z71 Suburban.

You must be registered for see images attach

Your stock wheels are 16X6.5 with an offset of 49mm (couldn't find center bore measurement but didn't look real hard either). These wheels on my K1500 are 18X8 with an offset of 31mm and the center bore is 78mm. No rubbing/interference issues whatsoever.

I would double check the specs of the wheel that you're looking to use on your truck but I would venture that you won't have any problems, I've seen many trucks with the newer OEM wheels on them.

Good luck!

Thank you. Without a garage to put it in, I have my work cut out to keep it washed and protected. I also checked out those wheels you have there, and they made it into my top 10. Your reply helped put me more at ease with the whole wheel decision. This is a pretty big choice for me. I have to decide what I want to get next and then save for it. I wasn't planning to buy new tires so early, so I'm stressing out a smidge.

 

[KennyP]

Regular-cab truck. Almost certainly JN3 brakes--the worst/weakest power brakes ever fitted to a GMT400-series truck.


Find an extended-cab, or a newer GMT400 with JN5/JB5, or JN/JB6 brakes. Grab the power booster, master cylinder, calipers, rotors, and hubs if not the entire steering knuckle.

Up front, the JN/JB5 and JN/JB6 brakes are the same, and much better than JN3.

In back, the JN/JB5 brakes suck exactly as much as the JN3. JN/JB6 rear brakes are MUCH better.



Probably a mistake unless you're using GM parts from a newer truck with a GVWR AT LEAST as high as what you have now.

If you have dreams of some aftermarket disc brake downgrade, think again. Takes REAL money to get a decent aftermarket rear disc conversion. There's heaps of crappy aftermarket rear disc conversions from multiple zero-engineering, rip-off artists companies, though.


Need? No. Want? Maybe.


Larger-diameter rotors means you need to space the caliper farther from the wheel center. Which means different steering knuckle, or some sort of kludged-up adapter brackets.

Good luck.

OTOH, calipers with bigger pistons would provide more force on the brake pads, AND you keep the existing steering knuckle, AND you can source JN/JB5 or 6 cores in the Treasure Yard for minimal investment.

When it was me, I took EVERYTHING except the rear axle from my JB5 extended-cab donor truck--booster, master cylinder, rotors, hubs, calipers.

You must be registered for see images attach

The rear axle came from a different donor.

You must be registered for see images attach

I can't help with wheels.

I can tell you that the single-best "brake" upgrade you can make is to throw the 254mm (10") leading-trailing shoe rear drum system in the scrapmetal bin, and upgrade the rears to the 11.x Duo-Servo brakes. This is even more important than upgrading the front brakes/booster/master cylinder as described above. (Of course, you could do both ends. I did.)

The BEST way to upgrade to the 11.x rear brakes is to scrap the entire rear axle in favor of a 6-lug, K2500 9.5" ring gear, semi-float axle of the proper gear ratio. Choose your core wisely, don't buy one that's got gear/bearing/brake problems, and make sure you get the U-bolt plates that go with the K2500 axle. You'll need a 447 conversion U-joint for the driveshaft, new U-bolts and nuts, and whatever repair parts the axle/brakes need to be serviceable, including park-brake cables if the ones on your truck are seized.

Regular-cab truck. Almost certainly JN3 brakes--the worst/weakest power brakes ever fitted to a GMT400-series truck.


Find an extended-cab, or a newer GMT400 with JN5/JB5, or JN/JB6 brakes. Grab the power booster, master cylinder, calipers, rotors, and hubs if not the entire steering knuckle.

Up front, the JN/JB5 and JN/JB6 brakes are the same, and much better than JN3.

In back, the JN/JB5 brakes suck exactly as much as the JN3. JN/JB6 rear brakes are MUCH better.



Probably a mistake unless you're using GM parts from a newer truck with a GVWR AT LEAST as high as what you have now.

If you have dreams of some aftermarket disc brake downgrade, think again. Takes REAL money to get a decent aftermarket rear disc conversion. There's heaps of crappy aftermarket rear disc conversions from multiple zero-engineering, rip-off artists companies, though.


Need? No. Want? Maybe.


Larger-diameter rotors means you need to space the caliper farther from the wheel center. Which means different steering knuckle, or some sort of kludged-up adapter brackets.

Good luck.

OTOH, calipers with bigger pistons would provide more force on the brake pads, AND you keep the existing steering knuckle, AND you can source JN/JB5 or 6 cores in the Treasure Yard for minimal investment.

When it was me, I took EVERYTHING except the rear axle from my JB5 extended-cab donor truck--booster, master cylinder, rotors, hubs, calipers.

You must be registered for see images attach

The rear axle came from a different donor.

You must be registered for see images attach

I can't help with wheels.

I can tell you that the single-best "brake" upgrade you can make is to throw the 254mm (10") leading-trailing shoe rear drum system in the scrapmetal bin, and upgrade the rears to the 11.x Duo-Servo brakes. This is even more important than upgrading the front brakes/booster/master cylinder as described above. (Of course, you could do both ends. I did.)

The BEST way to upgrade to the 11.x rear brakes is to scrap the entire rear axle in favor of a 6-lug, K2500 9.5" ring gear, semi-float axle of the proper gear ratio. Choose your core wisely, don't buy one that's got gear/bearing/brake problems, and make sure you get the U-bolt plates that go with the K2500 axle. You'll need a 447 conversion U-joint for the driveshaft, new U-bolts and nuts, and whatever repair parts the axle/brakes need to be serviceable, including park-brake cables if the ones on your truck are seized.

Sir, I tip my hat to you. A wealth of knowledge you are. You’ve given me the perfect foundation with part names to start off on the right foot. I had looked into those rear disk kits. You’re right, GM engineers spent a lot more time and money developing rear disk brake systems than these other companies “Bolt on” kits. Plus getting a larger rear end wouldn’t be too bad for a potential 383ci upgrade in the future. Thank you.