Click on the photo gallery here and go to the 18 KR wheel
http://www.fordvehicles.com/trucks/superduty/


what is the width of that 18 KR wheel and what is the offset and backspacing?

Thanks.

 

no one knows KR wheel specs?

 

The 08 King Ranch wheels are 20's.

 

Dude, they have 18's.

Click the gallery.

The 18's are stock KR.

I need width and offset.

 

If they still use the same tires as previous models. It's probably still an 18x8 with... if I remember right, a -6 offset.

 

The wheels are 18X8. The backspacing is 5.80".

 

The new trucks have a deeper offset IIRC. I want to say it's like 38mm positive.

 

You are close. The '05 - '08 factory 18X8's have a 40mm offset (positive). -6mm offset was pre-'05 wheels.

 

Thanks,

I was wondering if they were wide enough to run 37's because I can get a set cheap. Wheel width is recommended at least 8.5.


Do you think the 37's will wear unevenly on an 8" wheel?

 

what year truck do you have? It's nice to have your truck specs in your sig so people don't have to guess/ ask.

 

What tires are you looking at? It will depend on the width of the tire (actual mfr. spec.) as to how well it will wear.

Since you are looking at 37's, I am assuming you have atleast the factory snow plow package or a leveling kit?

 

The tire is 37X12.5 STT and recommended width is 8.5-11.

I have run a 35X13 on a 7.5" wheel and got real bad feathering.

I got an 05 250 V10 CC FX4 w/6" lift.

 

I assume that you are talking about 37x12.50R18 tires. If so, you'll probably be ok with the 18x8 wheels if you keep them properly inflated. I have known several people that mounted 35x12.50R15 tires on 15x8 wheels with no problems. This should be no different with the amount of sidewall that you will have. The big concern is that the bead seats properly.

Lesson Learned:
My first set of mud tires only lasted about 8,000 miles because I thought that the pressure listed on the side of the tire was what the pressure should be. Silly me! That's the "Max Load" rating. My 315/75R16 says "Max Load 3,195 lbs at 50 psi). I don't have that much weight on my tires, hence I don't need that much pressure. I used the public scale method to figure my tire pressure. The figures that I got were 37.5 psi in the front and 25 psi in the rear with no cargo in the bed. I have to adjust my pressure when I haul or tow, but most of the time this is the correct pressure. The main thing is to have the tread flat on the pavement. Then your tires will last the longest and perform like they were designed.

There is 2 ways you can figure out how much pressure to use. I used "Method 2" and I keep the graph in my glove box for reference.

Method 1:

• Set your truck up with whatever you will have in it most of the time.
• Take chalk and put a 4" wide strip across the tread of your tire.
• Drive about 50 feet in a parking lot and look at the chalk.
• If the chalk is worn off in the center, let out some pressure. If the chalk is worn off on the outsides, add air.
• Re-chalk the tire and repeat until the chalk wears off evenly. Then your pressure is correct.
• Repeat for all tires.

Method 2:

• Set your truck up with whatever you will have in it most of the time.
• Go to a public scale.
• Get the weight with only the front tires on the scale.
• Get the weight with only the rear tires on the scale.
• Make a graph (use graph paper) using the "Max Load" data on the sidewall of the tire. (example: Max Load 3,195 at 50 psi) Go up the side of the graph from 0-50 psi and from left to right on the bottom from 0-3,200 lbs. (I rounded up 5 lbs.)
• Draw a diagnal line from the 0 psi/0 lbs. intersection to the 50 psi/3,200 lbs. intersection.
• Take the weight obtained with only the front tires on the scale and divide by 2 (because there were 2 tires on the scale).
• Go right across the bottom of the graph to the weight obtained from dividing the front wieght in half.
• Go straight up until you hit the diagnal line.
• Go to the left and you will see what your front tire pressure should be.
• Take the weight obtained with only the rear tires on the scale and divide by 2.
• Go right across the bottom of the graph to the weight obtained from dividing the rear wieght in half.
• Go straight up until you hit the diagnal line.
• Go to the left and you will see what your front tire pressure should be.
• Adjust your tire pressure accordingly.

This may be a little confusing so I am posting some pics.

 

Decent post Mike11C... I agree that proper tire pressue is the key to good thread wear.

Although there are a couple things I would like to add.

First of all every tire has a load/inflation chart for it's particular size and the charts are used commonly among tire manufacturers. The best way to get one is by contacting your tire manufacturer.

For example this is the standardized load/inflation table for 315/75R16...

35psi - 2535 lbs.
40psi - 2715 lbs.
45psi - 2950 lbs.
50psi - 3195 lbs.

Second of all, when traveling on a regular basis at or above 70 mph you should add 5-10 psi above what is listed on the chart for your weight needs.

Third, never run a LT radial tire on the road at less than 35psi even if it is overkill based on a load/inflation table.

 

They do not have the 37X12.50 STT listed on Coopers site to get the exact width, but I am guessing that they are around 13". This should be no problem on the factory 8" wheel.

I have been running 35X12.50R18 Pro Comp Xtreme A/T's (also made by Cooper) on my stock 18X8's for over 15K now. Thread wear is excellent and even.