I have a 1997 F150, Over the last 2 years I have had all 5 lugs shear off and lost the drivers rear wheel...twice. Once while loaded and once while empty. The lug pattern is 5x135 mm with 12mm studs, I noticed that shortly after they went to a 14mm wheel stud. Did they have trouble with the 12mm studs not being strong enough? It is really annoying and dangerous loosing a wheel on the road, luckily i knew something was up and was pulled off to the side of the road going under 20 mph both times. Tow truck driver thinks the lug nuts were over torqued by the shop that put my tires on, you would think they would've known this might happen and design for it. Any thoughts?

By the way, the second time the wheel trashed the bed side and bent the bumper on the way out and the local Ford dealer put those tire on.
-Brad

 

You really have to watch those tire guys. The last time I bought tires they tightened mine so tight that a 250lb/ft impact gun wouldn't back them off. I had to "BOUNCE" on a 2ft breaker bar. I weight 175. Multiply that be 2 and add some for the bouncing and you are way over the 150lb/ft that is the correct torque. They will be wearing snow shoes in hell before I go back to that National company that sells Tires and I think they also sell Batteries.

 

Not the first I have heard of lugs breaking, IIRC the 12mm are only 95 or maybe 105 ft-lbs and the 14's are more. I doubt many if any tire places know and use the proper torque sticks on them. All 5 breaking tells me they were severely overtightened.

 

I had a 92 F150 with over sized tires that did the same thing. I had rotated the wheels and tightend them with a 4 way. The R. front snaped 4 out of 5 at 70 mph.. I replaced all 5 no prob.after that. Scott

 

Interesting, I found a recall about lug nuts loosening but I have had aftermarket wheels and lug nuts since i bought the truck 5 years ago. 1997 FORD F-150 Recalls

Is there a (somewhat) easy way to switch to 14mm studs or would this be a huge/expensive undertaking? Would my wheels fit back on? Would this require major surgery to the wheel flanges/hubs? Has anyone done this before? Would this make the axle any stronger? I use the truck to haul, and around the farm some, I want to make sure this doesn't happen a third time.
thanks
-Brad

 

i would say there is a 90% chance that your problem is due more to overtorque, than undersize studs. Considering that steel has a strength of 20,000 psi, i dont see how you could overload the truck enough to break the studs. YOu would have to have if REALLY LOADED, and hit REALLY BIG BUMPS. I would guess you would be breaking springs and frame brackets at that point.

 

Agree I just think tire shops are unaware of the smaller studs on the 97-98 f150s and they torque them to 14mm spec. If you have the 12mm you should probably remind them. There's a few tire shops around me and they don't seem to bright.

 

Odd, I would think the Ford dealer would know better but...

Anyway, someone suggested hardened wheel studs for running oversized tires, but I can't find any in 12mm X 1.75 thread, only in 1.5 thread. I'd like all the studs to match (threadwise). I would think that the hardened studs would also hold up a lot better to over torquing, right?
thanks
-Brad