I bought a 2014 M2 106 and it has all sorts of issues, need some advice

I would start at an actual Cummins shop for your engine troubles. The warranty is good there as well as at a Freightliner dealership. Any fault codes in an engine are an issue, especially while it is still under warranty!

Different series tire sizes between the front and rear axles should have no bearing on how something brakes, unless it is locked in four wheel drive, which does not apply to you. What possible reason did they give for changing tires with only 1100 miles on them?

 

Depends on your state law BUT heavy documentation is your friend here. You may have to claim a lemon with the dealer and get your money back / a new one. Find your states lemon law and own it inside and out. Have somebody start a log of every phone call , visit etc and keep times and people contacted all since day one.

If you cannot solve the problems and you need to send it back then follow the chain of command starting with the salesman working up to dealership GM. They will likely disown you too at some point.

Take that engine to Cummins ....document that too. Your going to have to own this problem and push it on ahead to whatever conclusion there is. If Dealer suspects you're trying to push for a lemon then he will likely try to ignore you or age your problems like sitting the truck in service for weeks. Don't let that happen. If you put it in for a problem then 48 hours is more than enough time to get it in a bay and looked at. If they sit it outside then pull it out of the shop and bring it back later under a new ticket / visit.

This is not a fun mule to ride either , good luck.

 

If you have fault codes there are problems! I'm willing to bet that no shop will put into writing that the fault codes, and I would make them list them by number, are of no concern. They are created because there is a problem. Have they been left in the system and not cleared from previous problems, or are they current and on going?

 

different size tires have a BIG difference in how a vehicle brakes.

keep 22's on the front and put 24's on the rear. you'll have poor brakeing. cuz the rears are spinning slower.

but, in the op's case. who knows what the circumference difference changed too with the different size he's got now.

 

Nope
each wheel should regulate itself.
The difference in size should not have any influence.
I think your truck has other issues.

Maybe best if you go with it yourself and arrange it so you are present in the workshop while they read the fault codes.
Make an appointement with the workshop or general manager for a certain date and time that they will work on it with you present.
Grab control over the situation at the dealer.

 

drive tires being 4 inches taller then the steers. there MAY be ABS issues. becuase 4 axles are spiinning slower then 2 axles.