Why are the wheel studs on my SUV breaking?

[ZenØHêåT]

It's a 2006 Ford Explorer XLT. We had the truck since 2006, in 2011 we had 22" rims put on. About a year in some months later all my rear studs except 1 broke off on the passenger side. We had them replaced, 3 weeks later 3/5 studs broke off the driver side in the front. I had them replaced except 1. The mechanic used a tool to install the studs on the truck. 1month later the same wheel has 3 broken studs. Why does this keep occurring? What should I do?
The mechanic is very experienced and did the second replacement not the first. He also used a torque wrench, unlike the first mechanics. Also I do hit corners hard at times and where I live the terrain is pretty awful. Lots of potholes, like I often check tire pressure when I hit potholes to ensure. So based on all your answers it could be a number of things. I think I'll remove the rims for awhile and put those factory rims back on.

 

[Tims]

I'd suspect that the bolt pattern is right but the centre bore of the new wheels is bigger than the old ones. That means that the studs are resisting shear for es instead of those being carried by the wheel centre and hub. Coupled with a lower offset that puts more strain in the bearings and bts you are loading them too much. It's not the torque. Mechanics aren't stupid and I e not met one who couldn't do this right!

 

[GeelMan]

cheap grade studs and also over torque is all I can figure,plus the wheels can be to big,,,,,,,,,,,,,,,,

 

[rufos_adventure]

the wheels may be stressing the lugs, are you cornering hard or hitting potholes or curbs?
your mechanic may be tightening them too tight, try torqueing them to factory specs instead of using the impact driver.

 

[scrubbag]

Maybe the wheels are being "torqued" down TOO much, putting a lot of strain on the bolts. If a torque wrench is used, it can be set to put too much torque on the bolts, and thus strip or break them.

I usually tighten my wheel bolts with a low torque on the air wrench, and then finalize the tightening, using a Hand Tool, and my muscle. This way, the bolts are snug, but not over tight.

Secondly, make sure that the bolts used are of the right strength....hardened bolts. Some aftermarket bolts ,might not be of the right strength, being made in some foreign country.

And last, maybe the steel wheels on your car, are putting too much strain on the bolts, by "flexing " too much.

Taller wheels, take more of the road force, because there is not as much "rubber" in the tires. What I mean, is that in a 22 inch wheel, with a total of 30 inches tall, that means only 4 inches of rubber on top and 4 inches of rubber on bottom, is the cushion....the rest is steel. With a 15 inch wheel, and 30 inch tall total height, then there is over 7 inches of rubber on the bottom and over 7 inches of rubber on the top, and so there is more cushion, and the tires can FLEX, taking some of the twisting force before it reaches the wheel.

Tall wheels are NICE looking, and allow quicker response to steering, since the rubber is not flexing as much....but again, more rubber means more...softer ride and road shock absorbing.

Make sure that the person putting on the nuts, does not OVER torque the nuts.

 

[JayBailey]

If they are breaking off from just riding on them then the lugnuts could be in a bind against the wheel. Replace them with the bullet/tuner style nuts for best results. Also make sure that the studs are long enough to reach all the way through the nut.