Some version of the same question comes up in the shop almost every week: if I put this on my truck, will it still pass inspection? It is a fair thing to ask, because Missouri’s safety inspection looks at several of the exact systems people modify — suspension, bumpers, glass, tires and lighting. Most of what we install has nothing to do with whether a vehicle passes. A short list of things does, and they are almost always avoidable if you know about them before the work starts.

Who Actually Needs an Inspection

Missouri does not inspect every vehicle every year, and a lot of people worry about a test they are not even subject to yet. A vehicle is exempt for the ten model years following its year of manufacture, as long as the odometer also reads under 150,000 miles. Both have to be true at the same time.

So a 2019 half-ton with 168,000 miles on it needs an inspection even though it is inside the ten-year window. A 2013 with 70,000 easy miles needs one too, because the ten years are up. Historic and antique-plated vehicles sit outside the program entirely, and trailers are not part of it either.

You generally run into the requirement at registration renewal and when a non-exempt vehicle is titled to a new owner. Worth knowing: the emissions test that much of the St. Louis metro deals with is a separate program from the safety inspection. Tint, wheels and suspension have nothing to do with emissions. If you just picked up something used, our first-week checklist for a used car covers the rest of what to sort out.

Timing is the easiest thing to control

If your renewal month is coming up and you are planning a build, get the inspection done first. It costs nothing extra and it takes the question off the table for two years.

What the Inspector Is Actually Checking

An inspection station works from a standardized checklist: brakes, steering, suspension, tires and wheels, lighting, glazing, mirrors, horn, wipers, exhaust, fuel system and bumpers. Nowhere on that list does it say anything about whether a part is factory.

That distinction matters. Aftermarket parts are not disqualifying by themselves. The question is always narrower: is a required item present, does it work, and is it within a legal dimension? A set of forged wheels is invisible to the process. A tire rubbing a fender liner is not.

Lift Kits, Leveling Kits and Bumper Height

This is the one that generates the most bad information. Missouri has no suspension lift limit and no frame height limit. What the state regulates, in RSMo 307.172, is bumper height — measured from a level surface to the highest point of the bottom of the bumper, with the vehicle unloaded and the tires at the manufacturer’s recommended pressure.

Two other pieces of that same statute are easy to miss. If your vehicle came with bumpers as standard equipment, it still has to have front and rear bumpers — drop bumpers are specifically allowed. And a body altered so the front or rear is raised at an angle that obstructs the driver’s view forward or rearward is prohibited on its own terms, independent of any measurement.

A vehicle in violation is not to be approved at inspection, and knowingly operating one is a class C misdemeanor. That is the whole legal picture, and it is a lot less dramatic than the internet makes it sound. The practical takeaway is simple: get a tape measure under the bumper before and after, and if you are close to the line, size the kit accordingly. If you are still deciding how much lift you actually want, our breakdown of leveling kits versus lift kits is a better starting point than a forum thread, and we can walk through lift kit options with your specific truck in front of us.

The part people forget: geometry

Suspension and steering are on the checklist. A lift installed without correcting alignment, brake line length and driveline angles can show up later as uneven tire wear or a component the inspector flags as loose. That is not a lift-kit problem, it is an installation problem — and it is the reason a lift is worth having done properly the first time.

Wheels, Tires and Fitment

Tires get rejected for the ordinary reasons: tread worn past the minimum, cord or belt showing, sidewall cuts and bulges, mismatched or damaged wheels, missing lug nuts. None of that changes because the wheels are aftermarket.

Where custom fitment causes trouble is contact. An aggressive offset that tucks the tire into the fender liner at full lock, or a tire that touches a control arm when the suspension compresses, is a genuine safety issue and an inspector can treat it as one. It also chews through expensive tires. This is the whole reason offset and backspacing get so much attention when we spec a set.

Two more things worth handling while you are at it. On a lifted or heavily loaded truck, make sure the tire’s load rating still suits the vehicle — going down in load range to get a tire you like is a bad trade. And if a tire pressure warning lamp is lit, get it sorted; a dash full of warning lights is never the impression you want to make at an inspection station. We can go through wheel and tire packages with fitment worked out before anything is ordered.

Window Tint and the 35 Percent Rule

Glazing is on the inspection checklist, which means tint is one of the few cosmetic modifications that can actually cost you a pass. Missouri’s limits are straightforward: front side windows have to let more than 35 percent of visible light through and cannot be more than 35 percent reflective. Back side windows and the rear glass can be as dark as you want. The windshield is limited to a non-reflective strip across the top six inches. If the back window is tinted, the vehicle needs dual side mirrors.

The trap is that factory privacy glass on the rear of an SUV looks dark, so people assume the fronts can match. They cannot, and a meter settles the argument in about three seconds. Missouri does allow a medical exemption with physician certification for drivers who qualify, but that is paperwork to arrange in advance, not something to explain on the spot.

We keep legal film on the shelf for exactly this reason and measure the glass before and after, so nobody leaves with a surprise. The full rundown lives in our guide to Missouri window tint laws, and if you want to compare films, we can show you ceramic, carbon and dyed side by side.

Bed Covers, Racks, Lights and Bumpers

Truck accessories are the least troublesome category on this list, but there are a few edges worth knowing.

Bed covers are essentially a non-issue. The only things to confirm are that the rear license plate stays visible and its lamp still works, and that nothing you bolted on blocks a required light or reflector. Retractable canisters and taller racks are where that occasionally comes up. Our overview of which bed cover fits which kind of driving goes deeper on the styles themselves, and we stock tonneau covers at all three shops.

Auxiliary lighting deserves more care than it usually gets. Forward-facing light bars are meant for off-road use, not as a substitute for headlamps on Manchester Road, and red or blue light showing to the front is reserved for emergency vehicles. Keep a bar covered or wired so it cannot be used on the street and you avoid the whole conversation. Exhaust is similar: the vehicle needs a muffler and it needs to not be excessively loud.

Bumper replacements circle back to the previous section. If the truck came with bumpers, it needs bumpers, and whatever you put on has to sit within the height limits.

If You Fail, What Happens Next

A rejection is not a disaster. The station hands you a sheet listing the specific items that failed, which is genuinely useful information — it is a diagnostic you just paid for. Fix what is on the list and bring the vehicle back. Ask the station about their re-inspection window; many will re-check a corrected vehicle at no charge if you return promptly.

The modification-related failures are almost all reversible. Film can be removed and reinstalled at a legal shade. Bumper height can be corrected. A rubbing tire is a fitment change, not a rebuild. The expensive version of this problem is only expensive when you find out about it after the parts are already on the truck.

Which is really the point of this whole article. Bring us the truck and the plan at the same time, and we will tell you before anything is ordered whether it puts you anywhere near a line. Most of the time it does not.

Frequently Asked Questions