Just like the title says, i just had a set of 270/70/18 installed on a set of 2018 Ram OEM rims. They fit great and really make the tires/rims proportionate to the truck.

The issue is the rear center caps do not fit properly. The fronts fit well, but the rear hub does not allow the caps to secure on the lug bolts.

Does anyone know what size lug nuts i need to extend them enough for the rear caps to lock on?

 

Which center cap are you trying to use? The center cap from the 1999 wheels or the 2018 center caps? I have late model 2001 aluminum wheels on my '96 Ram 2500 and have to use the 2001 center caps that are used with those wheels.

 

Good question...I've tried both my original 1999 caps and the newer 2018 caps. The 1999 caps spin and don't attach. I'm almost sure the lug nuts are original to the truck.

I'd rather use the newer 2018 caps.

 

The caps on my 2001 factory aluminum rims attached using 4 sets of clips that grab over four of the lug nuts. How do the 2018 caps attach? Do you have a photo of the front and back of the 2018 cap you can share here?

 

I don't have an application for you but try front and rear lugs...maybe for something like a '80's D60 front (Ford or Chevy 1T 4wd) or 10.25 rear, say a '95 F250 or something.

I think your threads are 9/16-18? So the only other critical spec is the diameter (and length, but slightly shorter is ok) of shank which presses into the hub

 

yes, factory specs on 1999 with 8 lug nuts is 9/16 - 18...where the newer lug from 2018 is metric, but appears longer by 1/2". This makes sense...if i can find a lug slightly longer in length then my current lugs.

I'll post some pics of the center caps in a few mins.

 

Here is what i found on rockauto....the newer lug appears longer in length and that is what i need, but in my 1999 size.

 

Pictured are the older 1999 which uses a secondary lip to hold the cap in place. the 2018 cap uses the lug bolt to hold in place.

 

The 1999 cap fits steel wheels, as it has a steel expansion ring that grabs against all 8 lugs to stay in-place. The later model 2001 cap that's used with aluminum wheels is more like your 2018 cap. I'm wondering if the hub on your rear axle is thicker/longer than the rear axles on the 2018 truck, since I seem to recall that Dodge moved away from using Dana axles in later years?

 

Good point as i've read where 2nd gen caps fit so maybe i'll look at the 2000-01 center caps for fitment.