16.00R20 Michelin tire shake at about 40 mph:

[MTVR]

The only issue we had on our trip, was that I had to avoid driving at 40 mph because of a significant tire shake in the front end that seemed centered right around 40 mph.

Our MTVR is an AMK23, so it was built as an armored truck, which means that it was built with run-flat inserts, and these appear to be the original tires with date codes from 2007, with no evidence that they've ever been off, so I strongly suspect that they're still in there.

The vehicle drives straight and the tires are wearing evenly. They've now got about 5,000 miles on them, and appear to be at about 90% tread depth.

Everything in the front end appears tight- the vehicle only had about 3,000 miles on it when we started this trip, and was in excellent condition overall.

I'm sure that the vehicle sat in some yard somewhere with the sun hitting the tires the same way every day, but there is nothing about the tires that looks uneven in terms of condition.

The tires appear round.

The onset of the shake starts at about 35 mph, and is pretty much gone by about 50 mph or so, and is almost imperceptible at the vehicle's top speed of 65 mph.

I spoke with Boyce Equipment when we were passing through, and they seemed to know exactly what I was talking about. They said all these vehicles do that, although the ones with runflat inserts do it the worst.

We do intend to replace the tires, but obviously we would like to avoid having this problem with the replacement tires too.

What can you guys share with me on this?

 

[simp5782]

Use fluid balancing first.

Not all tires do this. Ive logged more than 150k miles on 1600s with runflats from new to bald. And over 100k miles with 395s with runflats. Its just a balancing issue. Maybe a tire issue, to solve which one just move one steer tire at a time if the shake is in the steering wheel. Or if it's in the seat its from a rear tires. Easy isolation for the rear is to set the limp home rod on each tire or on 2 at a time.

Some places can spin balance them. Some can't.

You can fluid balance this way so you don't have to take it off the truck

 

[98G]

I suspect it may be just harmonics/resonance. I've got a truck that'll almost throw you out of the seat at 28mph, but is smooth until 25mph, and smooths out again at 32mph and remains smooth up to cruising speed of 60ish.

Also on 16.00s.

(By "smooth", I mean as smooth as one can expect from one of these behemoths.)