Thinking of changing tire size on my M923

[sniperboy]

I recently bought a M923a1 with the big (14x20 - Goodyear super singles - offroad tires). So far I'm not pleased with the ride. I think most of my trips are going to be on pavement. It drives nice in the dirt but on the road anything over 45mph gets kind of bumpy. After having several big 4x4"s with 38" superswampers I am familier with all the balancing issues with big off road tires. I'm new in the MV hobby (already hooked) and would like you guys to give me some ideas as to what my options are. I would like to stay with the rims I now have as my funds are limited.

 

[Beerslayer]

What tire pressure are you running? I dropped mine to 35 PSI and it rides better, thinking to drop another 5 lbs as the fronts still have the chicken bumps on the face of the tread on the outside.

 

[gringeltaube]

.......... on the road anything over 45mph gets kind of bumpy. ...................... I would like to stay with the rims I now have ..............

Yes, those 14.00R20 are tall heavyweights and as such will bounce and shake the whole truck around, at higher speed - if not correctly balanced! Most likely that is the real problem (only!)
Any other (smaller O.D.) tire option to fit your existing 20"x10" rims will weigh nearly as much and will do exactly the same...
And reducing tire pressure will eventually reduce the effect, but not eliminate the cause!

I also used to play with 40" D.Cepek's and 44" Superswampers..., and had to learn how to balance them myself (since in this country no tire shop would even look at them...)

Give it a try: simply balance - or have them balanced, statically! See how it's done, here.

I bet you will end loving your current tires...!


G.

 

[tiny110]

I put windshield washer fluid in all my tires. Make sure your windshield washer fluid has antifreeze in it. All you need is 20 ounces in each tire an it will balance them it will balance them out pretty good.

 

[sniperboy]

Thanks for the replies. I'll try the washer fluid first and see if it helps. I can tell that one of the tires has set for awhile and has a flat spot on it. I think that may be part of my problem. Since I've owned it I've had 2 tires come apart. The ones I replaced them with do seem to ride better. The cost of them set me back a little so I'll just save up and replace them one at a time.

A guy at one of the salvage yards told me I could go with the bigger Michlin tires. They are 53" tall and about an inch wider but about 100.00 each cheaper. After looking at the space between the rear tires I don't see how the bigger tires would fit. Like I said - I'm just starting out and have many ideas. I do appreciate the experience you guys at SS have. It's just like any other hobby "all it takes is money".

 

[Flat Black]

centramatic tire balancers

done

 

[M925Hound]

I to am having similar problems with my M925a2. I recently purchased the truck and at about 40 mph the truck begins shaking. It will bring itself in and out of the shake as you drive. I cant feel it in the steering but the entire truck will begin rocking and shaking around. It has new super single goodyears on it and the ctis has been removed off the truck. Fronts have about 80psi and rears have 55 psi. The shaking seems to be coming from the front of the truck. Anyone have any ideas?

 

[dawico]

If the CTIS system has been removed make sure the counter balance weights have been removed also. They are only on the front to counter the weight of the CTIS valve assembly.

I am new to this also and I blew a front tire. When I swapped it out I didn't change the weight over and my truck rode horrible. I haven't driven it yet with the weight moved so I can't say for sure it will make any difference, but it is a big weight.

If you do have to remove the weights air the tire down and get a big wrench. Those bolts are tight.

 

[VPed]

How about post no. 2 above. And drive often and long enough and to work out flat spotting. Those are for starters.

 

[M925Hound]

I will try removing the weight on the front wheels. The truck gets drove at least once a week between 20-50 miles. So flat spotting shouldn't be an issue. We have drove it up to 200 miles and it still does it. I was told that 80 psi is ideal for highway use! is that true for these trucks or not? thanks!!!

 

[Ford Mechanic]

I will try removing the weight on the front wheels. The truck gets drove at least once a week between 20-50 miles. So flat spotting shouldn't be an issue. We have drove it up to 200 miles and it still does it. I was told that 80 psi is ideal for highway use! is that true for these trucks or not? thanks!!!

I wouldn't exceed 85 psi, the tires are rated for far more but the rims have a max pressure note of 85 psi. Look for it on the front rims between the outer nuts. I have 70 psi in mine no issues here, I've hauled up to 7 tons in my truck. Seems like I saw a tire pressure spec sheet in a TM when reading the CTIS section, There may also be one in the cab on one of the data plates.

 

[Ford Mechanic]

I to am having similar problems with my M925a2. I recently purchased the truck and at about 40 mph the truck begins shaking. It will bring itself in and out of the shake as you drive. I cant feel it in the steering but the entire truck will begin rocking and shaking around. It has new super single goodyears on it and the ctis has been removed off the truck. Fronts have about 80psi and rears have 55 psi. The shaking seems to be coming from the front of the truck. Anyone have any ideas?

You may also need to rotate the tires also if there is any scalloping on the tread.

 

[hklvette]

80psi is overkill if you're not loaded to capacity, but for trucks with functional CTIS like mine you don't get much of a choice. That said, my 931A2 rides fine at anything but 27-33 and 58+mph. It "porpoises" like crazy at 30mph, so I avoid that completely. At the end of the day these trucks were designed to be hauling a load most of the time and the suspension is setup for that purpose. I doubt "ride quality" was even on the designers' and engineers' collective radar.

One last thing: if you have a truck with CTIS and intend to keep using it, its probably a good idea to stay away from balancing fluid so it doesn't work its way into the innards of the system.

 

[M925Hound]

Thanks for the info! I pulled the weights this evening and it seems to have fixed my problem!

 

[dawico]

Thanks for the info! I pulled the weights this evening and it seems to have fixed my problem!

I moved mine onto the tire I changed and took a little test drive. That made a huge difference.

 

[JingoJohn]

BEST SOLUTION: Load 4,500 pounds of sand bags in the bed.