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Old 07-22-2021, 06:57 PM   #1
Ziegelsteinfaust
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Slot mags vs pyo's

I am working slowly on my 83 C10 rcsb stepside to get her back on the road. After the unfortunate cooking of the engine due to a faulty temp guage. So today I was digging around one of my dads stashings, and found used slot mags. In my size even.

They are a staggard set with 15x7's, and 15x10's all with right around 4 inches of backspacing. I only quickly measured with a ruler I had quick access to off my weld cart. So if I go with them I will run 245/60's up front with 295/50's bringing up the rear. If I go with the pyo's I will switch to a 14 bolt SF, and a C30 front suspension. The tires would be 245/70r16, and 285/70r16 AT tires.

Obviously the C10's height would change. With the 15's a 3/5 drop would be about right. Where with the 16's a 1/4 would be about it. To accommodate the tire height differences, and keep the trucks level.

So for the question. While not the biggest tower of trailers. It is something I need to do often enough that I won't want to get rid of the prospects. As when I need to do it. It is often kind of last minute, and renting trucks becomes prohibitive when needed. How will 295/50r15's effect the feeling of towing? It has been 20 years since I towed with a old school C10 as I switched to C20's due to buy in cost, and larger brakes.
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Old 07-23-2021, 08:01 AM   #2
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Re: Slot mags vs pyo's

I would think the 295's would be just as stable as the 235/75r15's that came on it. I would think the load rating is close. I think it will tow just fine.
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Old 07-23-2021, 11:27 AM   #3
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Re: Slot mags vs pyo's

I hoped so, but tires are the biggest change we can make to our cars that effect everything.

I only have towed twice with a C10, but have towed around 100 times with various C20's I owned.
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Old 07-24-2021, 09:27 AM   #4
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Re: Slot mags vs pyo's

As far as towing, what gears are in the different rear ends? That will effect you overall pull and speedo accuracy. I like the stance of the 15" you described, but not sure what load the 295/50s are trated at when it goes to towing.. Lots of times the 60 and 50 series loose a good bit of weight compatibility compares to the 70/75 series tires of the same size.
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Old 07-24-2021, 10:31 AM   #5
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Re: Slot mags vs pyo's

All depends on what you are towing around? I towed with my 78 C10 short bed for years and years on 275/60r15 tires. But I only ever towed between 1500-2000 lbs. Tires held up just fine and the truck had 3:73 gears and factory heavy duty brakes. No problems once after thousands of miles with this combo.
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Old 07-24-2021, 12:33 PM   #6
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Re: Slot mags vs pyo's

rcsb and pyo's ... What are these please?
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Old 07-24-2021, 01:09 PM   #7
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Re: Slot mags vs pyo's

RCSB = Regular cab short bed

PYO is Factory GM wheels (aluminum I believe). Not sure what PYO is short for unless it is the SPID code for the wheels.
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Old 07-24-2021, 01:48 PM   #8
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Re: Slot mags vs pyo's

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Originally Posted by Corts60 View Post
All depends on what you are towing around? I towed with my 78 C10 short bed for years and years on 275/60r15 tires. But I only ever towed between 1500-2000 lbs. Tires held up just fine and the truck had 3:73 gears and factory heavy duty brakes. No problems once after thousands of miles with this combo.
It would be a car on a trailer. Or roughly 6-7000 pounds all in.

A big truck or van would likely need to be dolly towed to maintain weight limits.
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Old 07-24-2021, 03:36 PM   #9
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Re: Slot mags vs pyo's

That amount of weight is probably pushing it for a C10 in my opinion.
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Old 07-24-2021, 04:31 PM   #10
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Re: Slot mags vs pyo's

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That amount of weight is probably pushing it for a C10 in my opinion.
From what I can find online 7500lbs is max towing when properly equipped. Which it does not say what it is or means exactly.

I have a 12 bolt with big drum brakes. Probably like 12x2.5 inches, but I have not measured. The front breaks are the small 1/2 ton version, but if I keep it a C10. It will get the bigger rotors with Wilwood D52 calipers. Otherwise light duty C20 suspension pieces with the D52 calipers again. I have a rear airbag kit to be welded in once my mom tells me if I need to lower it. She is 80, and kind of short. So I will make this easy for her to get in, and out of safely. Likely it will get a 2/3 drop, but I am waiting for her word.

Plus the engine is good for around 465/475 minimum based on the build sheet, and original dyno tuning chart. The TH700r4 is a hybrid with 4L65e parts, and corvette servos. Along with a decent sized transmission cooler.

Most towing is withing 20 miles of my place, and with longer drives. I schedule it so it is before traffic or after. As it evolves coming down the Cajon pass. So I want to be as safe as possible. If it were a dually no sweat. Anytime would work.

I am more worried about the tires as they make or break the package. If I feel 15's won't get me where I need to be. I will just do the C20 suspension as I love the pyo rims as they are stupid lite.
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Old 07-24-2021, 07:05 PM   #11
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Re: Slot mags vs pyo's

For what it's worth, here's my thought process.

One, if I was towing that much weight regularly I would rather do it with a 3/4 ton. But that's not what you have, so you need to make that call.

Two, my guess is that you're going to find that the 295s are hobby tires and that you may need to step back to 285s or 275s to find a load rated tire. And then you would have to decide if you're okay with that look. If you can't find the tires in the size you like that are rated for the weight, then that for me would be a no-go. I think the slots would look sweet though.

Three, I think maybe you are talking about the py06 wheels. I like them too, but not really the offset on a square body. They are designed for axle widths on more modern trucks. The lightness of the wheels will be more than offset by the 14 bolt rear end and three quarter ton suspension.
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Old 07-24-2021, 10:45 PM   #12
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Re: Slot mags vs pyo's

3/4 ton suspension is less then 5 pounds heavier per side on the a-arms, and another pound or 2 for the cross shaft. Rims/tires not included, and selection does matter to round out a complete package. But alot of increased durability, and slightly larger disks. Of you need or want it obviously.

The 14 bolt SF is 20 maybe 30 pound heavier then a built 9", and overall still stronger. With out brakes. The only downside is C-clips, and no way to get rid of them I am aware of. Plus larger drums factory, and it can be a nice package.

The drop out 3rd member of a 9" is nice, but really it is overkill. With today's overdrive electronically controlled transmissions. I can gear it for a nice compromise of DD, and acceleration. Then the converter can bring the package home. With no pulling a 3rd member in a dash to get going.

I could get 8 lug axles for the 9", and ford 8.8. If I felt the weight advantage was worth it, but still durability goes to the 14sf. Plus I can still upgrade it decently with a locker, and better axles.

One of my visions for this truck was to make a surf, and sand muscle truck. If you watch Roadkill. They took the muscle truck to Glamis with bloggers, and hacked the fenders. But I would build one that won't get you pulled over all the time, and is actually still daily drivable. Which is why I gravitated to the C20 suspension swap.

Well today as I was routing my fuel lines, and installing my fuel cell. I realized I could get a pair of 33/12.50r15 tires for the rear, and leave the 30x9.5's up front. As a sort of compromise. It's just the truck 12 bolt has a weaker pinion then the car 12 bolt, and I don't want to spend.money then break it. Where now it is worth a few bucks to people who want a upgrade.

I intend to run rally cross events with the truck once I sort out the suspension. Even if there is no class I for into. A couple of local groups have a unlimited class for what ever people have. Since I plan to do it for fun anyways no trophy no care. Along with a cousin who has a ton of desert property. I can beat it like it owes me money.

Although a nice 4/6 drop would be sweet too. Probably just have to get another truck.

Right now I am spit balling ideas, and trying to gather info I do not have.

I tow maybe once a month close to home, and a time or two around a 80 miles.
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Old 07-25-2021, 12:46 AM   #13
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Re: Slot mags vs pyo's

This brochure may help you: http://brochures.slosh.com/pdfs/1986...Trailering.pdf

I agree on 6-7000lbs likely not being a legal tow weight for a C10. There are several factors you need to consider or can use to determine the safe tow weight for your truck::

• Gross Vehicle Weight Rating (truck weight + accessories + cargo + tongue weight cannot exceed this number)

• Gross Combined Weight Rating (truck weight + accessories + cargo + trailer/load weight cannot exceed this number)

• Maximum axle weight rating - The maximum allowed weight each axle can safely carry. These numbers combined should equal your GVWR, but limits how that weight can be distributed.

• Tire weight ratings - The maximum weight each tire can safety carry. These ratings should exceed GVWR when combined and each pair of tires on an axle should exceed the maximum axle rating.

• Maximum hitch towing capacity - The maximum amount of towed weight that can be safety attached to the hitch (or bumper). This number should be stamped on the hitch, and is usually the limiting factor on lighter duty towing systems.

If your load exceeds ANY of these stated limits, you are unsafe to tow.
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Old 07-25-2021, 11:17 AM   #14
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Re: Slot mags vs pyo's

Everything the truck has, and currently I am adding. From the 12 bolt rear, HD leaf spring pack, tranny cooler, helper air bags, and built engine tranny combo are capable of the job. Except the lite duty front spindles. Which I would get rid of either way.

As someone else mentioned 295/50's are play tires. So I looked up the specs, and they have the same weight capacity as 275/60's. Weight capacity only goes up decently when I get to 70 series tires.

The 295/50's have a 2061 pound capacity, and the 16's hover around 2700-2800 pound rating.

So if the 7500 max tow rating is true as I currently believe. The tires are good enough, but will I be pushing then to hard. And should just go to 16's with E rated tires.

While I had originally planned to build a dirt road bomber, a 4/6 drop C10 is also a big want.

I have a big love for slot mags, and would like to use them. Correspondingly adjust my plans.
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Old 07-25-2021, 11:20 AM   #15
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Re: Slot mags vs pyo's

Quote:
Originally Posted by Palf70Step View Post

PYO is Factory GM wheels (aluminum I believe). Not sure what PYO is short for unless it is the SPID code for the wheels.
Correct - it's just the RPO code for the wheel, like N67 (rally wheel) or C60 (air conditioning).

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Old 07-25-2021, 12:24 PM   #16
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Re: Slot mags vs pyo's

Thank you Keith
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Old 07-25-2021, 01:33 PM   #17
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Re: Slot mags vs pyo's

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Everything the truck has, and currently I am adding. From the 12 bolt rear, HD leaf spring pack, tranny cooler, helper air bags, and built engine tranny combo are capable of the job. Except the lite duty front spindles. Which I would get rid of either way.

As someone else mentioned 295/50's are play tires. So I looked up the specs, and they have the same weight capacity as 275/60's. Weight capacity only goes up decently when I get to 70 series tires.

The 295/50's have a 2061 pound capacity, and the 16's hover around 2700-2800 pound rating.

So if the 7500 max tow rating is true as I currently believe. The tires are good enough, but will I be pushing then to hard. And should just go to 16's with E rated tires.

While I had originally planned to build a dirt road bomber, a 4/6 drop C10 is also a big want.

I have a big love for slot mags, and would like to use them. Correspondingly adjust my plans.
What about brakes? Those are your most important towing component. Pulling the load isn’t the issue you are facing - most vehicles can physically pull a ridiculous amount of weight, far beyond any stated load ratings. The real issue is controlling and stopping the load. I think you are on the right path with your build, but two things I would highly recommend double checking before going too far are:

• Any factory GVWR/GCWR tag is going to be #1. No matter what modifications you perform to your truck to increase towing capacity, you cannot legally tow beyond what that tag states you can. A good example would be dropping a 1/2 ton cab on a 1 ton chassis - the 1 ton chassis has the capability of handling a 10,000lb GVWR load, but the 5,000lb GVWR tag states that is your max legal road weight. This is why most people will recommend moving to a heavier rated truck (3/4 ton) instead of modifying a 1/2 ton.

• Definitely check your intended tow hitch for it’s weight rating. Most frame mount hitches are only rated to tow 4-5,000lb loads. You can get ones rated much higher, just make sure you get the higher capacity when you order it.
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Old 07-25-2021, 01:52 PM   #18
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Re: Slot mags vs pyo's

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3/4 ton suspension is less then 5 pounds heavier per side on the a-arms, and another pound or 2 for the cross shaft. Rims/tires not included, and selection does matter to round out a complete package. But alot of increased durability, and slightly larger disks. Of you need or want it obviously.

The 14 bolt SF is 20 maybe 30 pound heavier then a built 9", and overall still stronger. With out brakes. The only downside is C-clips, and no way to get rid of them I am aware of. Plus larger drums factory, and it can be a nice package.
I assumed you would be using the one ton brakes and steering components as well. As for the rear end, I don't understand what a comparison to a 9-in has to do with it. Whatever the case, what you're describing to me sounds like an assortment of trucks. At least two, more likely three. Hope you settle on what you want. If you decide to run the 1 ton suspension and PYOs on the basis of saving weight, and it nets out less than half ton gear with aluminum slots, be sure to come back and post the update.

Last edited by LT7A; 07-25-2021 at 02:07 PM.
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Old 07-25-2021, 02:33 PM   #19
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Re: Slot mags vs pyo's

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I assumed you would be using the one ton brakes and steering components as well. As for the rear end, I don't understand what a comparison to a 9-in has to do with it. Whatever the case, what you're describing to me sounds like an assortment of trucks. At least two, more likely three. Hope you settle on what you want. If you decide to run the 1 ton suspension and PYOs on the basis of saving weight, and it nets out less than half ton gear with aluminum slots, be sure to come back and post the update.
I had originally planned to use C30 spindles for the larger calipers, but I have found out Wilwood D52 calipers work on a C20. Plus they are lite weight, and offer good clamping force.

C20 and C30 share the same ball joints, and tie rods. The only difference in the parts are the calipers, and matching spindles. Besides things like shocks, and spring rates. Which still interchange too.

I compared to the 9" because it is the standard by which axles are rated. Just like the standard sbc is the standard in engines for going on 50 years now. Things are starting to change, and maybe the LS architecture will displace it.

Yes it will be a Franken truck with parts from 3 different models to dial in want.

When I get it running I will post current pics as I have not taken any really currently.

Then I will start to make a final decision on which direction I will go. Because I am not buying parts for suspension at this point, and avoiding depression buying currently.
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Old 07-26-2021, 06:06 PM   #20
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Re: Slot mags vs pyo's

Running Cooper Cobras 295/50/15 all the way around on 15X10 Centerline wheels. The say standard load 2061 lbs. 935 kg max.

I haven't yet towed as I do not have a trans cooler. However, I will tell you the Coopers like 32 psi. Anything more and the front end starts to wander all over the road.
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Old 07-26-2021, 11:25 PM   #21
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Re: Slot mags vs pyo's

How do you feel the handling of tires are compared to more modern sizes?

Do you know the back spacing of the rims you got?
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Old 07-27-2021, 10:55 AM   #22
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Re: Slot mags vs pyo's

I have American Racing AR61 15x10 5x5 https://www.summitracing.com/parts/are-ar615173 The 4 inch backspacing gives the truck a real aggressive look. Everyone that sees it asks about the wheels.

Tires are Cooper Cobras I bought online. Started getting a really bad vibration at +75mph soon after it hit the road. (75mph is the slow lane of I-285 in Atlanta!) After many alignments, I did some research online, seems like Cooper has been having some issues with sidewall bubbles. One of mine original Cobras developed a bubble and I had it replaced locally. Vibration is still there but minimal.

I did notice that the font on the new tires white letters is different. Letters are laid back just slightly, almost italicized. I wouldn't have noticed until I compared the front and back tires on the same side of the truck!! UGH! Seems like they have changed between my first purchase and the second. Not sure what I will do now since its driving my OCD off the charts!! If I had it to do over again, I would have paid extra for BF Goodrich Radial T/As from the get go.

Other than the vibration, the truck rides nice. There is some bounce that modern cars do not have but that is expected with an '85 pickup. Grip is ok but my truck has an open rear and in the rain with no weight in the bed, it spins alot. Not sure on handling as I only have a front sway bar and stock springs. The tires seem fine and I'm sure lower sidewalls would be better but I just wanted the old school white letter look.

To complicate thing more, I never drove my truck on the stock sized rims and tires. Once it was running, it was on the new wheels and tires so I cannot compare to the original ones. Sorry.

Hope this helps
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Old 07-27-2021, 11:35 AM   #23
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Re: Slot mags vs pyo's

It does. I honestly have not had a C10 in 24 years. With my new C10 it has been 3 C10's, 4 C20's, 1 C30, and a F250.

I remember why I switched, but I don't remember if it was completely nessacary. What happened was I got a old Caltrans truck in near mint condition for $750 with a supposedly bad motor. It was a bad Q-jet with a leaking plug I believe. Either way it ran horrid. I put a new carb on it, and took a bunch of springs out of the rear. Plus a bunch of new replacement parts to make it nice again plus helper air bags. I was very happy with my $2000 dollar truck, but wished I had a C10 at that point.

So when I went with a friend to get a few engines we wanted to buy, and a car he wanted. It handled the weight so well that I never went back.

Now I am back Ina C10 because I had to have a Stepside, and found one stupid cheap.

So do I go with what I know to work the way I want. Or just polish up the C10 suspension because it will be good enough.
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