My 33" tires on Stock alloys are splitting??

[DK5]

Was going to mount them up for this summer and found a difference between the rears and fronts:
The front tires look like this (look at the middle)

The rears look like this:

I also noticed that they are "M" shaped. Maybe because its a 12.5" tire squeezed onto a 7" rim...

 

[DK5]

"M" Shaped:

Should I even worry about it?

 

[Russell]

The M shape is from running too much pressure in the tire. I probably wouldn't worry about the line down the center, though it is kinda unusual, LOL

 

[DK5]

yea! only on the front tires too.. maybe from turning sharply on dry pave? wierd.

 

[owenst7]

The M shape is from running too much pressure in the tire. I probably wouldn't worry about the line down the center, though it is kinda unusual, LOL

^^This

You're probably not over-inflating them based on weight of the truck per se, but the profile is crowned due to being squeezed on to the narrow rim (especially cuz they're radials). To get a square contact patch due to that crowning, they need to be somewhat under-inflated, which in an extreme case would be undesirable due to causing excess sidewall flex. The opposite would be more of an issue (assuming a radial), where the rim is too wide for the profile of the tire, and you would end up driving on the edges of the sidewall and not putting enough pressure on the tread face.

I used to have 17" wide Gumbos on 8" wide rims and the shoulder lugs wouldn't hardly touch the ground until they were aired down to like 10 psi...didn't need beadlocks though .

Should be fine if you drop the pressure 5 psi or so.

 

[DK5]

I've been running them that way for over a year now.. if I remember right I had it up to 25-30 psi. I'll try airing them down as soon as I get them mounted (after I figure out my steering problem).

Or should I bite the bullet and get some 10" rims.. I have a good excuse to do it now

 

[89 jimmy]

I would go with 8 in rims. I also have stock alloy 7 in rims and have 8,s as well. You can tell that the 8 in rims feel more stable cornering and overall. The seven in rim with 33,s prob has too much sidewall flex. I also had 10in rims but took them off shortly after, I just didnt like em. I am now runnin 32,s on my stock alloys at 35 psi.

 

[4xcrazy]

I could have swore I was told in the past by tire shops that when the center of the tire is sunk in more than the rest, this was due to underinflation, not enough air to push the tire out.

Had nothing to do with tire size on the rim, the sidewalls are what bulge out if the rim is too skinny.

 

[owenst7]

I could have swore I was told in the past by tire shops that when the center of the tire is sunk in more than the rest, this was due to underinflation, not enough air to push the tire out.

Had nothing to do with tire size on the rim, the sidewalls are what bulge out if the rim is too skinny.

Underinflation will cause you to ride on the shoulders of the tire and put less pressure on the center of the tread, but overinflating will cause the center tread to wear down faster.

 

[496truck]

Had nothing to do with tire size on the rim, the sidewalls are what bulge out if the rim is too skinny.

The sidewalls DO bulge out, but this effects the tread contact patch by pulling in on the corners of the tread.

Those 12.5 wide tires would fit and wear better on at least an 8" wide wheel. It's only 1" but it makes a difference.

 

[Blue85]

I bet those tires were just made in 2 different molds