New Tires for my F450

captainjohn2008 wrote:
I need new tires for my 2008 F450 C.C 4X4 Long Box 4.88 gear set. The originals are 225/70/R19.5. I would like to go to 245/70/R19.5 but the tire shop will not put them on as they say the dual tires will touch each other. There is currently 2" clearance between the 2 duals. The 245's are 1" wider, but to me that would mean 1/2" wider on each side of the tire leaving 1" clearance between the 2 tires. Am I wrong?? Has anyone else done this?? The truck has the aluminum rims. Thanks for advise. Cheers John.

Tell them do do it and have your RV in tow. Tell them if they touch you will pay them to remove them.

Does not make sense. What is the purpose of changing factory tire size?

I wouldnt do it...

Don't do it , not only will you need spacers which are hard to find for commercial trucks, but the rims on our trucks are only 6 inches wide which is too narrow for a 245 section width tire. I don't like the cookie cutter look either but safety over design any day.

They will fit fine, I am running the 245s on my 08 450 and there is lots of room between the duals. The larger diameter helps highway cruising speed to keep the rpms down with those 4:88 gears.

The tire specs from Continental. They might fit but safety dictates not to do it.


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Safety is very important to me and hopefully to you, as well. My OEM on my 08 F550 were 225. The weight I carry and the rough gravel and dirt roads just were not comfortable traveling down with the sidewalls bulging as much as they were. You mentioned that you measured and you have 2 inches of clearance with your present tires, but you should be aware with the 245 the face section of these tires are 1 inch or more, wider than the 225. So your clearance is going to be reduced. Then you will have the camber of the road and side loading these possible 245, your sidewall clearance will be even more greatly reduced.

No, I don't recommend that you put 245 on your OEM rims. Also, using spacers are just that, a "fix." I would never wish to reduce the thread surface by reducing the thread section holding onto my rims.

I bit the bullett and purchased Rickson Wheels, as well as new tires. I did offset this purchase by selling my OEM Tires/Wheels, including spare and front bumper. (Swapped it out for a Ranch Hand Bumper and 16.5 Warn Winch)

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245s fit. 225s drive better. We've done the back to test using two Ram 4500s which use the same axles and wheels and OEM tires are the Fords. Spacing isn't a problem (at least not with the tires we run... there is variation). But they are a little wide for the rims, and it caused less precise steering feel. The reason we upsized was to have uniform tire sizes among the 450/5500/650's in the fleet. Easier to manage tire inventory and maintain the stock of tire chains when all the tires match.

Also keep in mind that the factory Continental HDR/HSR tires lose speed rating as you go bigger. But, they are also the only brand that even has an option faster than 75 MPH.

Thanks for the reply's everyone. I usually change tire sizes from the factory size to personalize my rides and provide better handling appearence etc. My 450, I was hoping to lower RPM's at highway speeds as they are quite high with the 4:88 gear set. Also the wheel wells are HUGE on this truck and wanted to fill them up somewhat also. I am concerned about safety (I'm a professional firefighter, 32 years service, seen enough accidents to last several life times)so I think I'll just go with the factory size. I don't want to use a wheel spacer as the tires are now just barely inside the wheel wells and i'm too old for the tires to be "hanging out". Been there, done that! I just wish they'd make a tire that is taller in the same width. Not much available in this size i guess. This is my first dually and am still learning about some of these things,some limitations were never a problem with my single wheel trucks. Love this truck though. thanks again. Cheers John.