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Old 03-27-2014, 10:17 PM   #1
MikeB
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Pictures of your C10 tires

My "new to me" 82 SWB C10 has 6.5" Rally wheels (from a van?) and 255-70x15 tires that are nearly shot. The glove box sticker shows the truck originally came with FR78x15 tires, which are equivalent to 205-75x15. That sounds really small, but I know my 250 six would like their shorter height with the lame 2.73 axle, and my speedometer would be more accurate.

I'd appreciate pictures of trucks with 205-75, 215-75. and even 225-75 tires, if anyone has 'em. Also, what the heck, 235-70x15.
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1969 C10 LWB -- owned for 35 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, recent AAW wiring harness, 5-lug conversion, 1985 spindles and brakes.
1982 C10 SWB -- sold
1981 C10 Silverado LWB -- sold, but wish I still had it!
1969 C10 (not the current one) that I bought in the early 1980s. Paid $1200; sold for $1500 a few years later. Just a hint at the appreciation that was coming.
Retired as a factory automation products salesman.
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Last edited by MikeB; 03-27-2014 at 10:43 PM.
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Old 03-28-2014, 04:20 AM   #2
brakenit
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Re: Pictures of your C10 tires

Pretty sure my '84 was still sporting the stock size 205/75/15's when I got it.

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Old 03-28-2014, 06:14 AM   #3
D13
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Re: Pictures of your C10 tires

Mine are P235 75R15's, I can't imagine anything smaller withstanding the weight of my 6.2 diesel, or a BBC. That's on standard truck ralley's.
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Old 03-28-2014, 07:22 AM   #4
Keith Seymore
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Re: Pictures of your C10 tires

Base tires are really pretty small, because any money you can save per tire is multiplied by at least 4 (some trucks did not get a spare) or 5.

Here's mine with P235/75R15s on a 15x8 rally.

K



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Old 03-28-2014, 08:43 AM   #5
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Re: Pictures of your C10 tires

Thanks, guys. Keep 'em coming. Yeah, the 205s look awfully small in those big wheel wells!

I've had a few trucks over the years that ran 235-75x15, which has always been a popular size to run on pickups with 15" wheels. In fact, I initially thought I'd buy 235s, but then realized my axle is a 2.73, and wheel width is only 6.5".

Keith, what the heck was GM thinking when they made 2.73 the "standard" ratio for a 6-cylinder, manual trans pickup? The 3.50 1st gear makes it easy to get the truck rolling, but the gaps between gears is just nuts. Then again, my current 255-70 tires are 2" taller than a 205-75, which makes the 2.73 seem like 2.54.
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1969 C10 LWB -- owned for 35 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, recent AAW wiring harness, 5-lug conversion, 1985 spindles and brakes.
1982 C10 SWB -- sold
1981 C10 Silverado LWB -- sold, but wish I still had it!
1969 C10 (not the current one) that I bought in the early 1980s. Paid $1200; sold for $1500 a few years later. Just a hint at the appreciation that was coming.
Retired as a factory automation products salesman.
Worked part-time over the years for an engine builder and a classic car repair shop.
Member here for 24 years! This is the very first car/truck Internet forum I joined. I still used a dial-up modem back then!

Last edited by MikeB; 03-28-2014 at 08:48 AM.
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Old 03-28-2014, 08:49 AM   #6
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Re: Pictures of your C10 tires

my truck has 225 75 R 15 tires on it pics while it was still a project
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Old 03-28-2014, 11:32 AM   #7
Keith Seymore
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Re: Pictures of your C10 tires

Quote:
Originally Posted by MikeB View Post
Keith, what the heck was GM thinking when they made 2.73 the "standard" ratio for a 6-cylinder, manual trans pickup? The 3.50 1st gear makes it easy to get the truck rolling, but the gaps between gears is just nuts. Then again, my current 255-70 tires are 2" taller than a 205-75, which makes the 2.73 seem like 2.54.
Fuel economy!

I always start at 3.42 and then move from there when choosing an axle ratio. 3.42 and 3.73 pretty much cover all my needs.

K
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Old 03-28-2014, 05:26 PM   #8
MikeB
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Re: Pictures of your C10 tires

Quote:
Originally Posted by Keith Seymore View Post
Fuel economy!

I always start at 3.42 and then move from there when choosing an axle ratio. 3.42 and 3.73 pretty much cover all my needs.

K
I didn't know CAFE standards applied to light trucks.

Yeah, my little 250 six would probably like 3.73, but not on the highway! I'm thinking shorter tires for the time being, and maybe 3.23-3.42 gears if I keep the six. I've done R+P swaps on two 10-bolts and one 12-bolt, so I'm armed and dangerous!

Back in the late 80s I had an 81 C-10 with 305, TH350C, and 2.56 axle (!). If the T/C locked up at speeds less than 40-45 mph, the entire truck would shudder. Drove it around in 2nd gear a lot, until I installed an under-dash switch to control the lock-up. And I only engaged the switch when driving at highway speeds.
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1969 C10 LWB -- owned for 35 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, recent AAW wiring harness, 5-lug conversion, 1985 spindles and brakes.
1982 C10 SWB -- sold
1981 C10 Silverado LWB -- sold, but wish I still had it!
1969 C10 (not the current one) that I bought in the early 1980s. Paid $1200; sold for $1500 a few years later. Just a hint at the appreciation that was coming.
Retired as a factory automation products salesman.
Worked part-time over the years for an engine builder and a classic car repair shop.
Member here for 24 years! This is the very first car/truck Internet forum I joined. I still used a dial-up modem back then!
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Old 03-28-2014, 10:48 AM   #9
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Re: Pictures of your C10 tires

235 75 15
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Old 03-28-2014, 10:53 AM   #10
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Re: Pictures of your C10 tires

225 70 front and 235 75 rear. Originals where 205 75's.
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