Should my steer tires be at least within 5 units of tread depth .. for the two?

Toss both of them into the trailer spares pile.

Put two nice steers matched on the front axle. Then check for balance, alingment etc. When everything is in spec, that should be the end of your tire story.

Those two tires are the most precious and important ever anywhere on that rig. Do not accept nothing but the best.

Anything else is negligent BS when you bust one and cross the double yellow to kill a family.

Your boss is going to spend a dollar. Either that or you will. But when the morning comes, your truck is in good shape and #### near a dream to drive. How motivating is that?

 

The tread depth isn't as big a problem as the mismatch in brands. Those two tires have a different rolling resistance and tread pattern, and that makes them fight against each other. That will make the front end want to wobble around, and it will likely cause both to wear more rapidly and unevenly.

Whoever replaced just the one steer tire without a matching tire was a moron.

 

Mismatched steers are a problem waiting to happen.

That low tread steer needs to go on a trailer, and if a good match can't be found for the higher tread steer, it should be pulled and used as a matching spare for someone else's truck after your truck gets a matched pair of steers.

Mismatched steers wear poorly, and can cause front end vibration.

 

Seriously?

Ok after doing this for a while, here is the ONLY problem I see.

It isn't the tread depth

It isn't the mismatched brand

It isn't the rolling resistance

The only thing that you need to be concern about is this ...

If you have two different size tires on the steer axle.

That's it.

If they are the same size ... meaning the numbers match, make sure they are inflated the same and drive the truck.

As for the steering ... unless it is sloppy while driving straight and flat, then I would just ask for an alignment and see what happens.

 

If there is a difference of 8/32 tread depth, then the tire diameters are 16/32 different from one another.

Half an inch might not sound like much, but it is a fair chunk of the diameter of a truck tire.

Yes, you can run on them, but you want that truck to do at least 500k miles before it needs to be replaced, right? Why expose the truck to long term, easily correctable, uneven stresses to the steering and suspension systems?

It's like changing the oil. Sure, you can get away with skipping an oil change here and there, and the truck won't catastrophically fail, but why expose your investment to more wear and invite preventable service issues?

 

What stresses?

There is so much more stress put on the steering components with road surface irregularities than uneven tires.

 

If the truck is always at a slant across the steers because of different tire diameters, then the entire truck frame will always be slightly out of alignment.

All load bearing components will be absorbing stresses slightly differently than how they were designed to take them.

A huge difference? No. However, trucks are optimized to absorb stresses based on their ideal blueprint configuration. If you want the best life from the truck, you should avoid asymmetrical loading unless absolutely necessary.

 

The mismatched tread depth has nothing to do with it, nor the overall height either. The dufference between the 2 brands could be more than 8/32'sw.

I have to wonder if the truck has only 75,000 miles on it, why has it got two different steer tires on it.
Putting the low tread one on the trailer and trying to find a match for the other one is a joke too, put 2 NEW steer tires on it when it needs tires, unless you ruin one that is brand new. I hate to put one drive tire on , but will to get home, but steers, it is 2 at a time for sure.

 

Having different brands on steers might certainly cause more complexity if their virgin heights and tread depths are not the same.

As for why one tire is so far off from the other in tread depth at only 75k miles. I suspect a road hazard damaged one, or perhaps one had a defect that only turned up after some wear.