Walk through any tire shop and you'll see two of what looks like the same tire — one labeled 'OEM' and one not — at different prices. Sometimes the OEM is cheaper, sometimes the aftermarket is. The actual difference matters more than the label.
What 'OEM' means
OEM stands for original equipment manufacturer. An OEM tire is the specific tire model and spec that came on your car when it left the factory. Automakers work with tire makers for years to tune a tire for the exact suspension, weight, and intended character of each model.
OEM tires often have a small star, asterisk, or letter code on the sidewall identifying which automaker spec'd them: a star for BMW (the asterisk *), MO for Mercedes, N0/N1/N2 for Porsche, and so on.
What you give up going aftermarket
OEM-spec tires are usually tuned for specific characteristics the car was designed around: ride comfort, noise level, specific handling balance, fuel economy. An aftermarket replacement of the same brand and model — but without the OEM spec — may have a slightly different compound or sidewall, and may feel different on your car.
What you might gain going aftermarket
OEM tires often emphasize ride quality, fuel economy, and rolling resistance to help the manufacturer hit EPA targets. Aftermarket tires can prioritize different things — more grip, longer life, better wet performance, lower noise — sometimes outperforming OEM in real-world driving.
When OEM matters most
- Performance cars where the suspension was tuned with a specific tire (especially Porsches with N-spec)
- Run-flat-equipped cars where the OEM spec dictates run-flat compatibility
- Plug-in hybrids and EVs with low-rolling-resistance OEM tires (range will drop with aftermarket)
- Cars under warranty (some warranties get fussy about non-OEM tires)
When OEM matters least
- Standard sedans and crossovers where the OEM is a mid-tier all-season
- Older cars (5+ years) where OEM specs aren't as relevant
- Cases where the OEM tire has been discontinued
Used-tire reality
OEM-spec used tires are common in the used market because they come off cars early as part of trade-ins. They're often a great value — a Porsche N0 Michelin Pilot Sport at half retail is a remarkable buy if you have a Porsche. Just verify the OEM marking matches what your car actually needs.
OEM isn't a guarantee of quality — it's a guarantee of compatibility.