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Old 04-25-2014, 09:21 PM   #1
CST10
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Stock tire height?

What was the stock tire height in inches for a 1970 C10? We're they the same height for all the years. I currently have some 28" tall tires on it.
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Old 04-25-2014, 10:07 PM   #2
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Re: Stock tire height?

If your stock tires are 235/75-15 then the height is 28.88" The circumference is 90.72"
If you need other sizes see this site. >>> http://www.tacomaworld.com/forum/tir...ires=235-75r15
Just curious, What are you trying to determine? If it's for a speedo set up there's a special way you need to measure tire height. (NOT from ground to top)
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Old 04-25-2014, 10:07 PM   #3
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Re: Stock tire height?

G78/15B was the minimum stock tire in 70. Those run about 27.75".
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Old 04-25-2014, 10:53 PM   #4
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Re: Stock tire height?

It's for the speedo. How do you measure for the correct wheel diameter height other than the ground up?
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Samson the 1970 CST10, LWB, 462Ci, Turbo 350 tranny, 3.08 rear gear, PB, PS, A/C, AM/FM, 2/4 Drop.
Brutus the 1998 Camaro Z28, 33,500 original miles, LS1, 519 RWHP/497 RWTQ.
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Old 04-25-2014, 11:08 PM   #5
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Re: Stock tire height?

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Originally Posted by CST10 View Post
It's for the speedo. How do you measure for the correct wheel diameter height other than the ground up?
because the tire "Squats" at the bottom you actually have two tire diameters. One is unloaded (Laying on it's side inflated) And the other is Loaded (With the weight of the truck sitting on it) Measure from the ground to the center of the wheel and times that by 2. This gives you the true running diameter of your tire.
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Old 04-25-2014, 11:30 PM   #6
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Re: Stock tire height?

Here's a good site to get all the info and parts you'll need.


http://www.transmissioncenter.net/sp...____va.htm#350
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Old 04-25-2014, 11:33 PM   #7
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Re: Stock tire height?

Quote:
Originally Posted by CST10 View Post
It's for the speedo. How do you measure for the correct wheel diameter height other than the ground up?
Rather than try to measure or eyeball it, go to http://www.tirerack.com/index.jsp or the tire manufacturer's website. Enter your tire's designated size and it will show the physical dimensions, among other details. FWIW, the actual size of the tire can vary a bit brand-to-brand.
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Old 04-26-2014, 12:00 AM   #8
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Re: Stock tire height?

Quote:
Originally Posted by Stocker View Post
Rather than try to measure or eyeball it, go to http://www.tirerack.com/index.jsp or the tire manufacturer's website. Enter your tire's designated size and it will show the physical dimensions, among other details. FWIW, the actual size of the tire can vary a bit brand-to-brand.
You can do this. However, this will give you the unloaded tire size and NOT what you need to calculate speedo gears.
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Old 04-26-2014, 07:08 PM   #9
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Re: Stock tire height?

Well I measured the squared tires. It came out doubling them to 26 1/2". Is that about right for stock height tires?
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Brutus the 1998 Camaro Z28, 33,500 original miles, LS1, 519 RWHP/497 RWTQ.
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Old 04-26-2014, 08:07 PM   #10
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Re: Stock tire height?

26.5 sounds about right. I'm not sure what you mean by "Squared tires" though.
You just need to measure up from the ground to the center point and then times that number by 2.
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Old 04-27-2014, 08:34 AM   #11
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Re: Stock tire height?

Lol. I meant squatted tires. Lol. Auto correct and no reading glasses on. It's a terrible thing. Lol. Thanks for the info on the tires. I was wondering what it should be. Since I'm close the speedo must be off in the tranny gearing for the cable.
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Goldilocks the "Ol School Survivor" 1968 C10, SWB Stepside, 08/15 TOTM, 250 CI 6 cylinder, 3 on the tree, 3.73 rear, 3/5 static drop, 23,500 original miles.
Samson the 1970 CST10, LWB, 462Ci, Turbo 350 tranny, 3.08 rear gear, PB, PS, A/C, AM/FM, 2/4 Drop.
Brutus the 1998 Camaro Z28, 33,500 original miles, LS1, 519 RWHP/497 RWTQ.
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Member of the Louisiana C10 Club
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Old 04-27-2014, 11:32 AM   #12
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Re: Stock tire height?

Quote:
Originally Posted by CST10 View Post
Lol. I meant squatted tires. Lol. Auto correct and no reading glasses on. It's a terrible thing. Lol. Thanks for the info on the tires. I was wondering what it should be. Since I'm close the speedo must be off in the tranny gearing for the cable.
Ah... I understand. I suffer from short arm syndrome also. lol
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Old 04-27-2014, 12:34 PM   #13
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Re: Stock tire height?

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Originally Posted by BADAZ chevy guy View Post
You can do this. However, this will give you the unloaded tire size and NOT what you need to calculate speedo gears.
Maybe I'm wrong, but I hafta disagree with you on this. When calculating speedo gears, you're not going by the height of the tire, but by the overall circumference. And whether the tire is loaded or unloaded, the circumference ain't gonna change.
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Old 04-27-2014, 12:53 PM   #14
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Re: Stock tire height?

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Originally Posted by Sicklajoie View Post
Maybe I'm wrong, but I hafta disagree with you on this. When calculating speedo gears, you're not going by the height of the tire, but by the overall circumference. And whether the tire is loaded or unloaded, the circumference ain't gonna change.
This isn't just my opinion. I found this way of determining tire height here. >>> http://www.transmissioncenter.net/sp...____va.htm#350

This is from their website. "To determine your tires true diameter in relation to determining what speedometer gears you need, measure from the ground up to the center of the axle then multiply by two. The actual run out of the tire can be as much as 2 to 3 inches less than what the circumference of the tire measures. In effect your tire has two diameters."
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Old 04-28-2014, 08:33 PM   #15
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Re: Stock tire height?

Quote:
Originally Posted by Sicklajoie View Post
Maybe I'm wrong, but I hafta disagree with you on this. When calculating speedo gears, you're not going by the height of the tire, but by the overall circumference. And whether the tire is loaded or unloaded, the circumference ain't gonna change.

Agree with this.....
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Old 04-28-2014, 08:46 PM   #16
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Re: Stock tire height?

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Originally Posted by Econman View Post
Agree with this.....
Read my post just above yours. This way of measuring the tires is from a very reputable speedometer shop. >>> http://www.transmissioncenter.net/sp...____va.htm#350
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Old 04-28-2014, 08:52 PM   #17
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Re: Stock tire height?

Link would not connect to their site
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Old 04-28-2014, 08:59 PM   #18
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Re: Stock tire height?

Quote:
Originally Posted by Econman View Post
Link would not connect to their site
This one should work.
http://www.transmissioncenter.net/sp...____va.htm#350

This is from there site on how to measure tires to determine which gears you need.
"To determine your tires true diameter in relation to determining what speedometer gears you need, measure from the ground up to the center of the axle then multiply by two. The actual run out of the tire can be as much as 2 to 3 inches less than what the circumference of the tire measures. In effect your tire has two diameters."
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Old 04-28-2014, 09:03 PM   #19
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Re: Stock tire height?

It is probably easier and more accurate to just grab a GPS and see what the actual speed is compared to your speedo... if you are 10% off just change the speedo gear to get the number of teeth you need for to make it right, or just buy an adapter with the correct % correction. No need to measure tire height, unless you are buying new tires anyway and want to get back to stock height.

Look here for gears and ratio adapters:
http://www.partshp.com/speedometer_gears.htm
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