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02-18-2024, 04:39 PM
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#1 |
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Senior Member
 
Join Date: Jul 2000
Location: North Texas
Posts: 3,425
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tire sizes
My 69 C10 currently has 255-70X15 tires front and back on 8" wheels. I've been looking at ways to reduce highway revs a little w/o going to an OD trans. Axle ratio is 3.08, so there's nowhere to go from there.
What do you guys think about 32x10.5x15 tires in the rear? Looks like they will reduce RPM by 240 RPM at 70mph. I'd probably put the same brand/model tires on the front in size 235-75x15. How would the truck look? I can handle criticism fairly well.  BTW, the engine is a mild 350 with TH350 trans. I am not worried about "getting off the line" in a hurry.
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Mike 1969 C10 LWB -- owned for 34 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, 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 23 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; 02-19-2024 at 11:46 AM. |
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02-18-2024, 11:55 PM
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#2 |
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Registered User
Join Date: Oct 2023
Location: Waterloo Iowa
Posts: 243
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Re: tire sizes
I just did 31x10.50-15s with a a 1” drop front and 3” drop in rear. If yours isn’t dropped, you should be able to fit it.
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02-19-2024, 11:48 AM
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#3 | |
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Senior Member
Join Date: Jul 2000
Location: North Texas
Posts: 3,425
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Re: tire sizes
Quote:
Here's how mine looks now with 255-70x15s.
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Mike 1969 C10 LWB -- owned for 34 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, 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 23 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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02-19-2024, 12:56 PM
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#4 |
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Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,515
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Re: tire sizes
Easiest and cheapest way is to reduce speed to 64 mph. A 6mph drop equals about 240 rpm.
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02-19-2024, 01:26 PM
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#5 | |
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Senior Member
Join Date: Jul 2000
Location: North Texas
Posts: 3,425
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Re: tire sizes
Quote:
Back in the days of 55-65 mph speed limits, I put several thousand freeway miles on the truck. Heck, now a 70 mph speed limit essentially means 75-80 here in Texas, which the truck simply doesn't like. Funny, because I remember driving freeways in cars with 27" tires and 3.7x gears back in the day, and we never even thought about needing another gear. Had a friend with 4.11 gears in a 60s Corvette who used to drive a 500 mile round trip twice a month to see his girlfriend. He said the same thing -- he doesn't remember the high revs being an issue. Heck, I'll probably just end up with an OD trans, but then my 3.08 gears will be a little tall. Damned if I do...
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Mike 1969 C10 LWB -- owned for 34 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, 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 23 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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02-19-2024, 03:20 PM
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#6 | |
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Registered User
Join Date: Oct 2023
Location: Waterloo Iowa
Posts: 243
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Re: tire sizes
Quote:
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02-19-2024, 04:04 PM
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#7 |
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Registered User
Join Date: Sep 2011
Location: Ark City, Kansas
Posts: 3,280
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Re: tire sizes
What's that white stuff on the ground???
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02-19-2024, 04:19 PM
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#8 |
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Post Whore
Join Date: Feb 2016
Location: Portland Oregon
Posts: 10,805
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Re: tire sizes
Why not pick up a pair of cheap used tires off Craigslist or a wrecking yard and give them a test then if your not happy you're not out any serious cash.
__________________
Thanks to Bob and Jeanie and everyone else at Superior Performance for all their great help.  RIP Bob Parks. 1967 Burban the WMB,1991 S(stink)-10 Blazer,1969 GTO, 1970 Javelin, 1952 F2 Ford 4X4, 29 Model A, 72 Firebird. 85 Alfa Romeo If it breaks I didn't want it in the first place The WMB repair thread http://67-72chevytrucks.com/vboard/s...d.php?t=698377 |
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02-19-2024, 06:42 PM
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#9 | |
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Senior Member
Join Date: Jul 2000
Location: North Texas
Posts: 3,425
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Re: tire sizes
Quote:
__________________
Mike 1969 C10 LWB -- owned for 34 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, 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 23 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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