The correct conversion for 6.70-15 is 205/75/15 or 215/70/15. If you have power steering I heard that the 215's will be harder to turn. Both are wider that the originals. Why do you think the 205's are too small? Is that just your opinion of how they would look or that they would physically be too small?

 

Will putting bigger tires on, affect the speedometer?

 

Mainly its just my opinion. To me, even the 215's look a bit small on a truck.
This is just based on what I think looks "right"

(Take that and .50 cents and you might be able to get a coke somewhere)

Bobby

 

Bobby you are showing your age, .50 cents won't buy no stinking coke these days. Maybe you can have a sip especially if it's warm!

 

I am pretty sure stock wheels for a F-1 are 16". If you are running 15" it's going to throw your speedo off. I am I wrong about the 16"?

 

Ok, I found a website: http://www.4crawler.com/Diesel/Tires.shtml that actually lists the tires I have, but they give a funky equivalence, that I'm not sure what to do with. It says that r78/15=37X12.5 Anybody know how that translates to modern tire sizing?

Thanks

 

LOL... and I'm just a puppy. I might be getting older but I'm still just as immature as I ever was. Teh coke machine in my garage is .15 cents (it sure keeps longnecks cold)

The tire size in question here R/78/15 doesn't make sense. As someone pointed out earlier there should be another letter on the tire in front of the "R". If I remeber right, the "R" just designates that the tire is a radial.

If you google tire conversion, or tire calculator you will find some interesting reading about all this malarky. Here are a few links;
http://www.tireguides.com/tip5.html
http://www.net-comber.com/tirecalc.html
http://www.csgnetwork.com/tireinfo4calc.html

I think you should send a PM to rhopper, the man is a tire genius

Bobby

 

Standard F1 tires were 6.00-16 4-Ply, options were 6.00-16 6-Ply and 6.50-16 6-Ply

All were mounted on 16 x 4 1/2 Wheels

The 16 x 41/2 wheels were standard on 1948 - 1964 F1/F100

 

I don't know if anyone has looked here.

http://dbtires.com/index.htm

 

I'm resigned to put this thing on hold for a few weeks. I'm in a condensed class right now, and then the regular semester starts, and it'll take a few weeks to get everything sorted out. After that I'll take the 5hr drive to go down and check everything over and get all the information I can.

I'll let you all know what I find out then. I thought this would be a quicker simpler deal--maybe I'll find that "key" when I get down there.

Thanks all!

 

I would call Coker and ask them what size tires should be on the truck. That would be the base to start with. I would also as them what would cross over to todays sizes in a radial etc... I found them very helpful when I bought mine. Almost any 16 inch tire will fit on any 16 inch rim within reason, but it sonds like the PO might have been on a tight budget and put on whatever he could find. Whatever you do, don't run radials and non radials together.

In my youth, I had a '68 LTD station wagon and work in a service station and if someone came in and got new tires and one of the old had some life left in it, if it fit my rims, it was on my car. I ran f-78-15's with h78-15 or j78-15. I did find that with the H or J on the front, when I made a turn, the tire rubbed the fender well. Call Coker and ask them. It can't hurt

 

Blue50, that r78-15 you're refering to is a little used 4wd size. Basically a "monster mudder". Back in the day...we used to have n78,p78, and q78-15 in our product line, but no r78-15. It's just a coincidence that you found that size on that web site, it's not what we run on our trucks. The 37x12.50 means 37inches tall, with a 12.5 inch wide section. Dick's right, the oe was a 600-16, which right now means either a cheap chinese nylon trailer tire, or Coker. But lots of those old trucks got converted into whatever was around.

 

Thanks. I'll just find something (tire/wheel combo) with an equivalent circumference to the OE then. I appreciate your help.

 

Just a thought if your looking for tires for your 66 merc remember o.e. was a 15 inch tire. I'm using P215/75R15 coker w/w radials on my 54 merc. You may want to call them about the correct size.

Chuck

 

Id be willing to bet that that R is really an F as the F78x15 was a very common OEM fiberglass bias ply in the 65-75 era and is still a popular trailer tire. I run the 14" versions on my 53 Vicky to get it lower.