Tall 15" tires?

[jagarra]

I am looking for some tall 15" tires to fit my 62 GMC, most I have found are in the 29-30" range. Does anyone know of a manufacturer that has something a bit bigger in diameter? I have a 3;54 rear end ratio, SM420 tranny.

thanks

[James]

You might have to go with a larger rim. I went with 16" rims and my tire diameter is 31.7". I too have a 3.54:1 rear axle and a SM420 transmission.

[jagarra]

James,

You may be right, from all the looking I have done the best is 30.5" diameter and that was in a snow tire. Problem is that I have original 3 piece rims with hub caps that I don't want to give up. Probability is that I won't take it much on highway anyway so it would be hard to justify buying all new rims and tires for an extra 5-7mph on the road.

thanks,

gg

[James]

According to my numbers with a 30.5" tire you will have:
2150 rpm = 55 mph
2350 rpm = 60 mph
2550 rpm = 65 mph
2750 rpm = 70 mph

With a 29" tire:
2250 rpm = 55 mph
2450 rpm = 60 mph
2650 rpm = 65 mph
2850 rpm = 70 mph

On my truck with 16" rims and a 31.7" tire:
2050 rpm = 55 mph
2250 rpm = 60 mph
2450 rpm = 65 mph
2650 rpm = 70 mph

All of these numbers should be within ±2 mph.
There is not a lot of different between the tire sizes. So whatever you decide to use, it is not going to make a big difference.

[63gmc4x4]

Im running 31x10.5 on min 8 wide wheel lowered 4 inches no rubbing

[BillT]

Not sure of the height, but I needed a taller tire for the Rears on my '72 C-10. I am using 265/75/15's. Not a whole lot, but it did make a difference.

[James]

Originally Posted by 63gmc4x4

Im running 31x10.5 on min 8 wide wheel lowered 4 inches no rubbing

According to the info I found online for this tire size it is approx. 30.67" dia.

Hope this is helpful.

[jagarra]

I decided to go with an option that let me keep the 3 piece rims. When I purchased the truck two tires were shot so I replaced them with new keeping the best of the ones left on there, I matched a set of Lee tires for the front. I believe these tires are pretty old and I have been getting the square tire ride for the first hour or so of operation. So I ordered some mud/snow tires from STA (30") that will go on the rear and the ones purchased a couple years ago will go on the front. This should give me some rubber that should last for awhile. I do have a set of chrome spoked wheels that are 15x8" diameter that came with truck if I decide to go to tubeless radials.

[jagarra]

Finally received my snows for the back of my truck after waiting for a few months for delivery. As I mentioned previously, I have the original 3 piece rims on my truck, now the joy of changing the tires on them began. First of all they had a 3 digit date code with the last digit being a 5. Googling the Lee brand showed they were discontinued by Good Year in around 1980. So they may be from 1975 date and been on there for 47 years. No wonder they felt square.
The tires were basically rusted to the rims, after the retaining ring was removed nothing moved. I inflated the tire a bit with the retainer removed so the outside rim portion raised a bit above the edge and smacked it a number of times with a dead blow hammer to break it from the tire. that was easy compared to the reverse side. The tire was mounted on my 60s era manual Coates tire changer, A unit I used when I worked in service stations when in high school, a lot of effort and many rotations lifting from the underside finally broke the bottom free and the tire/tube assembly was removed. Much time was spent removing rust the the outside rim and rim of the wheel, they may have spent time laying on the ground flat so the water seeped into the interior of the wheel and rusted everything, after some time wire brushing every surface and using a grinder with a scotch brite pad attachment the rim was clean on the inside. We are now ready for the tire installation. looks like i am out of room, cont........

[jagarra]

Now on to the the preparing the tire installation. The tires have a tube, and another item called a liner that protects the tube from touching the inside surface of the rim. One has to first install the tube, inflate it to straighten out the creases and let the air out, then the liner is installed, it is pretty wide and goes down each side of the tube about 4", repeat the inflation deflation routine again to get everything to seat. Now position the tire on the rim and slide the valve nozzle into the hole on the rim and the tire assembly will slide onto the rim with no efforts. Nice not having to pry over the outside rim. the outside rim is positioned over the hub, the lock ring goes on top and then the outside of the rim is pushed down the hub for abut 2-3 inches exposing the groove in the rim for the retaining ring. the ring is positioned by prying over the edge onto the groove all the way around. After it snaps into place it is OK to inflate your tire.
I ended up using tires from Specialty Tire of America, I was so happy with the installation I ordered 2 new highway ones for the front too.

Interesting note, I priced the tires from Coker and they quoted shipping of $150, but when I ordered them from Jegs, shipping was free, same price per unit.