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Wheels, Tires, Suspension and Brakes Keep them doggies rollin', rawhide

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Old June 5th, 2016, 10:06 PM
Chuck78 Chuck78 is offline
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Default 15" tire sizes/brands for GMC 1000 Big Block v6?

I'm looking for guidance / opinions on tire selection for the front of my 1962 GMC 1000 Panel Truck. 2 wheel drive 1/2 ton.

With an 800 lb GMC big block V6, I have been looking considerably at the load ratings of tires when considering them. I remember once reading the weight of my panel truck at 4,000lbs, but wondered if that was a chevy or i-6 weight. My 1989 Suburban weighed 5,000lbs but had full interior & rear seating and lots more wheelbase, and heavier automatic trans, but lighter 350 sbc v8.
I will be hauling light to medium loads every few weeks/months - 1 to 4 motorcycles 250-530lbs/ea, lumber, remodeling & landscaping supplies, engines...
I might tow a car + dolly/trailer once every 6 months to 2 years, not regularly.

My favorite classic road gripper Firestone Firehawk Indy 500 is no longer available in 15"
I still have four 50% tread 275/60r15 Firestone Indy 500's on 15x8 5 lug Torque Thrusts for the rear. 28" tall, so my fronts cannot exceed this diameter.
For now, front is 6 lug 15x7 wheels until I swap my 5 lug disc brake setup on. Then I will use the other 2 15x8 Torque Thrusts that currently have 275/60R15's mounted (4 total, 2 currently on the redrilled Dana 44 axles in back).
My rear Firestone 275/60R15's have a load rating of 2,149lbs (107S) which is pretty substantial for a musclecar type tire.

I have a narrow size range to meet the criteria of 28" height or less, and fitting 15x7 & 15x8 wheels. This narrows it down to basically a 28" 235/70R15 and 27.1" 255/60R15.
It has very old rotted G60-15's (245/60-25) which look ok but slightly too small diameter. I had to lower the ride height of the torsion bar suspension to get it to look acceptable in the bigger front fenderwell.

Last edited by Chuck78; June 6th, 2016 at 04:11 AM.
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Old June 5th, 2016, 10:20 PM
Chuck78 Chuck78 is offline
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Default Re: 15" tire sizes/brands for GMC 1000 Big Block v6?

Cooper Cobra Radial GT's Any better than BFG Radial T/A?
255/60/15
27.1" tall - sporty & better than current size, closer to the 28" rears to fill bigger front wheel wells better
1,885lb load rating - best I've seen in this size
235/70-15
28" tall same as rears, fills ft wheel wells better
1,896lb load rating - not much more than 255/60
440AB tread rating, a bit softer than "highway/touring" tires, should be a better gripper
*the classic look! Get this in the taller / higher load rating 235/70-15 & swap it to the 15x8 5 5 lugs when I convert? or run slightly less load rating in 255/60-15 now & / or later on the 15x8 5 lug swap? (better fit on 8" than 235/70)
$100/ea




Mickey Thompson Sportsman S/T Radials
255/60-15

1,885lb load rating
$130
*I would've guesed this to be best gripper of the bunch, but had to look it up on a US DOT pdf to even find the treadwear rating, 440AB, same as Cooper Cobra. You know, these look identical to the Cooper Cobra aside from the very outside treads being in the shape of an "M" for Mickey! Same tread wear rating and same load rating!
Also very high load rating for this size.
*not available in the truck oriented 235/70-15


BFGoodrich Radial T/A
255/60R15

1,885lb load rating
400AB treadwear/wet traction (softer than Cooper Cobra & it's sibling the Mickey Thompson Sportsman, more $ 150/ea)
235/70R15
1,896lb load rating
$130/ea)
(Really between these 2 sizes it comes down to wider grip vs easier steering+filling up fenderwell aesthetically better without lowering suspension slightly)



Maxxis Marauder MA-S1 235/70-15
At 1,926lbs, highest load rating in this size
Reviews say semi-noisy to really noisy for an all season tire.
360AB treadwear/wet traction rating - 30,000mi treadlife, big plus, I want most road grip possible not longevity. All season very grippy looking street tread. one review said it squirms a little in turns.

$100 ea
255/60-15 is rated at 1,874lbs







In searching for a tire in that size with an XL rating, the only things I could find where a Hankook Tire and this other Maxxis Tire:

MAXXIS HT-770 BRAVO SERIES 235/70R15-XL
1,929lbs Load Rating
Increased casing stiffness XL rated truck tire
640AB treadwear/wet braking rating (high mileage tire)
$104/ea
* perhaps it would be a bad idea to mix and match a stiffer claimed truck tire like this on the front with a high load rating 60 series wide width muscle car tire in the rear? This seems like it would be an awesome daily driver tire for 3/4 ton trucks that get worked, running 15x7 all around



https://youtu.be/0k0xMklkvlE

I did note however that this tire has basically the same weight load rating as the others that I was considering. It does specifically advertises stiffer casing. It will fit my 15x8 rims, but ideally a 15x7 would be best. I'll give this some careful consideration, but I wonder if the 1/2" shorter sidewall 255/60R15 would corner just as good as this thicker casing taller profile tire? Or is it just as thick as the other ones with a similar load rating?

Last edited by Chuck78; June 6th, 2016 at 04:17 AM.
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Old June 5th, 2016, 10:56 PM
Chuck78 Chuck78 is offline
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Default Re: 15" tire sizes/brands for GMC 1000 Big Block v6?

It comes down to the's options/questions:

*Can I do just fine running the higher load rating passenger car (musclecar/sporty truck) tires as long as I keep the load ratings in mind and go for the highest within my criteria?
Or should I really be running XL rated thicker ply truck tires? I have the musclecar type on the rear until they wear out, including the 2 spares.


*Do I run a 28" tall 235/70-15 with its slightly higher load rating since I have monstrously heavy big block V6's over the front tires, or is a very slightly lesser load rating 27.1" tall 255/60-15 going to do just as well?
For the full 2149lb 107S rating on all corners I could even eventually (after 5 lug disc swap) run all 4 15x8 275/60-15.

***Is a 275/60-15 on front going to be an absolute burden to steer/parallel park with manual steering & tiny 14" Indy woodgrain steering wheel? 255/60 for that matter?
I am a stickler for simplicity, & these giant GMC truck engines are gas hogs - a power steering pump is going to detract a bit from my fuel economy! I want to be able to do long road trips and get over 20 MPG as I previously have on this with the 305D V6 without overdrive. Bigger 351C v6 & overdrive coming soon. I do have an OEM 60's GMC power steering pump somewhere, and a power steering box attached to the 73-91 Suburban disc brake crossmember... it would surely make for a more sporty ride.


*If going 255/60R15 (or 275), since I'm swapping the 15x7 6 lugs late summer for 5 lug15x8's & discs, should I just throw on some $17 junkyard Michelin tires for now? Then upgrade to a high quality 255/60-15 later?

*Or run good quality 255/60-15 on the 15x7 now, swap them to the 15x8 5 lug wheels when doing 5 lug disc conversion, will have 2 spare rear 275/60-15's to dismount off the 2 spare 15x8's if I get the good tires now


*Are Cooper Cobra Radial GT's any better than BFG TA Radials??? They cost slightly less

Last edited by Chuck78; June 5th, 2016 at 11:24 PM.
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Old June 6th, 2016, 03:20 AM
bobdylan bobdylan is offline
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Default Re: 15" tire sizes/brands for GMC 1000 Big Block v6?

I like the 215 75R 15 for the standard 15x7 rim. I am looking at kumho AT51 8 ply rating, 2095 load, 27.6 inch diam. I like the narrow look on the old trucks.
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