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| | | | Joined: Mar 2003 Posts: 313 'Bolter | | 'Bolter Joined: Mar 2003 Posts: 313 | My speedometer registers on the slow side, both in the mileage and speed. My tires are 28 inchs high. I need to replace all the tires and the 6.50 x 16 that Cokers sells run between 29.25 to 29.40 inchs high. Will that solve the speedometer being inaccurate? | | | | | Joined: Oct 2003 Posts: 19 Apprentice | | Apprentice Joined: Oct 2003 Posts: 19 | If you are physically going faster than your speedo indicates, and are covering more distance than your odo indicates, then...if all other things are correct on your vehicle, you actually need a smaller circumference tire to correct this. How far "off" is your speedo & odo right now? | | | 
#3927 02/24/2004 11:42 AM | Joined: Mar 2003 Posts: 313 'Bolter | | 'Bolter Joined: Mar 2003 Posts: 313 | At 30 mph on speedo, actual speed is about 35 mph. A mile on odo is actually 1.25 miles. | | | | | Joined: Sep 2003 Posts: 1,820 Shop Shark | | Shop Shark Joined: Sep 2003 Posts: 1,820 | Before I made any tire size or buying decisions, I would find a good speedometer shop and have the speedometer checked out to be sure it is working correctly and that is calibrated correctly.
Just a thought.
"Truckin' Around .......... Since 1937!" My name is Joe and I am addicted to Classic Country Music. I just can't hep myself.Operators are standing by to take your calls! Now cruising in the Passing Lane | | | | | Joined: Jun 2003 Posts: 56 Member | | Member Joined: Jun 2003 Posts: 56 | The larger diameter tire will make your speedometer and odometer even more inaccurate.
Since these old timers are so slow anyway I don't think it makes much difference, just get the tires you want then worry about the calibration.
'31 Chevy 1 1/2 ton,
'42 GMC 2 1/2 ton 6x4,
'52 GMC 2 1/2 ton 6x6,
'53 GMC 5 ton
| | | | | Joined: Jun 2003 Posts: 56 Member | | Member Joined: Jun 2003 Posts: 56 | The larger diameter tire will make your speedometer and odometer even more inaccurate.
Since these old timers are so slow anyway I don't think it makes much difference, just get the tires you want then worry about the calibration.
'31 Chevy 1 1/2 ton,
'42 GMC 2 1/2 ton 6x4,
'52 GMC 2 1/2 ton 6x6,
'53 GMC 5 ton
| | | | | Joined: Jun 2003 Posts: 56 Member | | Member Joined: Jun 2003 Posts: 56 | The larger diameter tire will make your speedometer and odometer even more inaccurate.
Since these old timers are so slow anyway I don't think it makes much difference, just get the tires you want then worry about the calibration.
'31 Chevy 1 1/2 ton,
'42 GMC 2 1/2 ton 6x4,
'52 GMC 2 1/2 ton 6x6,
'53 GMC 5 ton
| | | | | Joined: Jun 2003 Posts: 56 Member | | Member Joined: Jun 2003 Posts: 56 | Sorry about the triple post. I kept trying to go back and evidently every time I clicked "Back" it posted again. Netscape finally locked up.
'31 Chevy 1 1/2 ton,
'42 GMC 2 1/2 ton 6x4,
'52 GMC 2 1/2 ton 6x6,
'53 GMC 5 ton
| | | | | Joined: Nov 2002 Posts: 394 'Bolter | | 'Bolter Joined: Nov 2002 Posts: 394 | Along with your your tire size I'm considering going to a 6.50x16" tire on my 55' 1/2 ton truck. Would there be a problem upgrading from my stock 6.70x15" tires, and what is the actual width of a 6.50x16" rim? I'm not even sure what the width of my 6.70x15" rims are? My intent is to lower the rpms.The 3.90 gears tend to run those rpms. up ther mighty quick. THANKS ALOT THERE AMIGOS  | | | | | Joined: Sep 2001 Posts: 29,269 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,269 | ol' 55,
The original 6.70 x 15, 4 ply passenger-style tire had a 28" outer diameter (unloaded) and a 5" rim width.
The original 6.50 x 16, 6 ply truck tire had a 29.10" outer diameter (unloaded) and a 5" rim width.
Wheel offsets were approximately the same.
Tim | | | | | Joined: Nov 2002 Posts: 394 'Bolter | | 'Bolter Joined: Nov 2002 Posts: 394 | Thanks for your reply on the 16" rim size there Tcledermen, I am now looking for 4 of them at my buddys place and junk yards. ol' 55. | | | | | Joined: Dec 2001 Posts: 1,745 Member | | Member Joined: Dec 2001 Posts: 1,745 | I was looking at tire sizes last night. I have nice new BF Goodrich's that the PO put on. They are like 28 plus inches tall. I believe 235/70R15 if I remember correctly. I noticed on the BF Goodrich website that you can actually get taller sized tires for the 15 inch rim than for the 16 inchers.
I saw that the tire I have goes up to 285/70/R15 at 30.8 inches tall. I am thinking of selling two of my tires and buying two of the tall ones for the rear. It should be good for another couple hundred rpm.
After that height they change the way they write them up. Next comes a 31/10.5/R15 and even taller but these are only available in offroad treads.
54 3100 with 235
62 flatbed dump C60 with 261
| | | | | Joined: Mar 2002 Posts: 384 Shop Shark | | Shop Shark Joined: Mar 2002 Posts: 384 | I put on a powerking tire 31" dia. It was about $70 ea. I'm considering going to a 33" snow/mud that is available from Power King also. They are bias tires and 6 or 8 ply. I put them on my 16" original wheels. I used to have a 27.5" dia. tire, and it made a noticable difference. I heard that out west, they like the bias tires and large dia. for some reason. Maybe there are others available. - Scott
55 1st Chev.
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#3938 03/02/2004 12:56 AM | Joined: Jan 2004 Posts: 103 Shop Shark | | Shop Shark Joined: Jan 2004 Posts: 103 | I got a set of RY215 yokohama 7.00X15-8ply from the tire rack that are 29.4" tall. radial all season light truck. | | |
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