The seller says the tires have plenty of life — how do I verify that?

Measure the tread yourself: 1.6 mm is the legal minimum in the US and UK, and 3 mm is the sensible replacement line for wet roads. Then read the DOT date code — anything over six years old needs a closer look, and ten years is retirement age regardless of depth.

Does a resprayed panel always mean the car was crashed?

No — but paint over 200 µm, or a 40-50 µm difference between panels, confirms filler or a respray is present. Cosmetic resprays happen; the reading simply forces the seller to explain which panels and why.

Can I skip the compression test if the engine sounds healthy?

Sound tells you little about ring or valve wear — only numbers do. A cylinder more than 10-15% below the strongest fails, and the teaspoon-of-oil retest separates a ring problem from a valve problem.

The car has no service stickers at all — is that a deal-breaker?

It means the oil interval is unknown, not that the car is bad. Treat the oil and brake fluid as overdue — brake fluid older than 2-3 years needs a flush — and reflect that near-term work in your offer.

The pre-purchase checklist

Premier Motors KY — Buying a used car from a | premiermotorsky.com

Check the paperwork first — title, VIN and recall status — then the cold engine, then the metal and fluids, and only then take the drive. Each check below carries a stated threshold in millimetres, micrometres or degrees, so the decision to buy, renegotiate or walk away is made by numbers, not impressions.

Paper

Title, VIN and recall status come before any tool leaves your pocket. The 17-character VIN must match in three places, and its 10th character must agree with the stated model year.

Metal

Cold start, then the walkaround: tread depth and DOT dates on all four tires, pad thickness and rotor lips, paint depth panel by panel. Each reading has a stated pass line.

Road

The drive is a 15-minute route with named checks — fan cycle, braking from about 50 km/h, straight-line drift — and a look underneath once the car is back and hot.

The order matters as much as the checks: paperwork first, cold start second, drive last.

Every threshold here is a number you can measure in the seller's driveway with an inexpensive gauge.

Start with the paperwork: title, VIN and recalls

A car that fails on paper never reaches the driveway checks.

The VIN is 17 characters, and the letters I, O and Q never appear — if you think you see one, you are misreading a 1 or a 0. The 10th character codes the model year and repeats on a 30-year cycle: A means 1980 or 2010, F means 1985 or 2015, so the car's paperwork must agree with the code.

Check the VIN in three places — the dash plate, the door-jamb sticker and the title — and treat any mismatch as the end of the visit. Run the VIN for open recalls before money is discussed; an unresolved recall is the seller's problem to fix, not yours.

Ask for the service history next. A dated oil sticker lets you judge the interval — 5,000-7,500 miles (8,000-12,000 km) on conventional oil, up to 10,000-15,000 miles (16,000-24,000 km) or 12 months on full synthetic. No dated sticker means the interval is unknown, and unknown gets treated as overdue.

Read the car, not the ad

Six readings, each with a stated pass line — anything past the line reprices or ends the deal.

The key terms of this guide, drawn to one scale

The numbers that decide the deal

The thresholds that decide a used-car deal — measure each one before money is discussed.
What you measure	A pass looks like	The deal-breaker
Tire tread depth	3 mm or more for wet roads	1.6 mm — legal minimum, wear bars flush
Tire age (DOT code)	Under 6 years old	10 years — retire regardless of tread
Brake-pad friction material	10-12 mm when new	3 mm — replacement due
Rotor edge wear lip	Under 1 mm	1-2 mm deep — rotor due for renewal
Paint depth	80-150 µm, factory finish	Over 200 µm, or 40-50 µm between panels
Compression spread	Within 10% of the strongest cylinder	More than 10-15% below the strongest
Brake-fluid age	Under 2 years	2-3 years — flush due; wet boil is 155 °C
Engine-oil interval	Dated sticker within 5,000-7,500 mi (conventional) or 10,000-15,000 mi (synthetic)	No dated sticker — interval unknown

The thresholds that decide a used-car deal — measure each one before money is discussed.

Objections buyers actually raise

The seller says the tires have plenty of life — how do I verify that?: Measure the tread yourself: 1.6 mm is the legal minimum in the US and UK, and 3 mm is the sensible replacement line for wet roads. Then read the DOT date code — anything over six years old needs a closer look, and ten years is retirement age regardless of depth.
Does a resprayed panel always mean the car was crashed?: No — but paint over 200 µm, or a 40-50 µm difference between panels, confirms filler or a respray is present. Cosmetic resprays happen; the reading simply forces the seller to explain which panels and why.
Can I skip the compression test if the engine sounds healthy?: Sound tells you little about ring or valve wear — only numbers do. A cylinder more than 10-15% below the strongest fails, and the teaspoon-of-oil retest separates a ring problem from a valve problem.
The car has no service stickers at all — is that a deal-breaker?: It means the oil interval is unknown, not that the car is bad. Treat the oil and brake fluid as overdue — brake fluid older than 2-3 years needs a flush — and reflect that near-term work in your offer.