1991 BMW 318is Speaker Sizes
The 1991 BMW 318is factory audio system includes front door panel and rear door panel locations that accommodate 5.25 inch speakers. Midbass and full-range units serve as compatible speaker types during a replacement or upgrade procedure for a 5.25 inch speaker size.
Specific details regarding locations, speaker sizes, and types are outlined in the compatibility chart.
| Location | Size | Type | Notes |
|---|---|---|---|
| Front Door Panel | 5.25 | Midbass / Full-Range |
|
| Rear Door Panel | 5.25 | Midbass / Full-Range |
|
1991 BMW 318is Speaker Replacement Summary
2
total positions
2
easy to replace
1
high priority
0
professional only
Replacement difficulty:
Low: 2 Medium: 0 High: 0Replacement priority:
High: 1 Medium: 1 Low: 01991 BMW 318is Radio Slot Size (DIN)
| DIN Type | Size (inch) | Size (mm) | Notes |
|---|---|---|---|
| Single DIN | 7"×2" | 180×50 | Standard size for basic car radios with small display or no display |
- Always measure the slot before purchasing a new radio
- Check slot depth - it may vary
Additional Notes
- The 1991 BMW 318is uses 5.25 inch speakers in both front and rear door panels, accepting either midbass or full-range types. This uniform sizing throughout the door positions may simplify replacement planning when upgrading the factory audio system.
- Full-range speakers can reproduce a broader frequency spectrum from a single driver unit, while midbass speakers focus on mid and lower frequency reproduction. The choice between these compatible types depends on whether the system includes separate tweeters or relies on individual speakers to handle the entire audio range.
- Replacing door panel speakers in the 1991 BMW 318is could potentially address common issues with factory audio systems from this era, such as deteriorated speaker cones, worn surrounds, or reduced sensitivity from aging voice coils.
- The single DIN radio opening provides a standard installation footprint that accommodates most aftermarket head units. This configuration allows for modern source components while retaining the original speaker locations in the door panels.
- Midbass speakers typically require a crossover network or external amplifier to filter frequencies properly, whereas full-range speakers incorporate internal components to distribute audio across their intended spectrum. This technical distinction influences installation complexity and component selection.
- Speaker replacement in door panel locations may improve clarity in vocal reproduction and instrumental detail compared to factory units, particularly if the original components have experienced foam rot or cone separation over time.