Car Tire Size / Car battery size / Group 51R
Group 51R battery size
A group 51R car battery is at most 9.37 inches long, 5.08 wide and 8.78 tall (238 x 129 x 223 mm), with top posts.
- Length
- 9.37 in (238 mm)
- Width
- 5.08 in (129 mm)
- Height
- 8.78 in (223 mm)
- Terminals
- top posts
Same box, other group numbers
- Group 51: 9.37 x 5.08 x 8.78 in, different terminal layout (BCI figure 10, not 11).
Same box does not mean same battery: if the terminals are on the other side, the cables may not reach.
Before you buy a group 51R battery
- Read the group number on the label of the battery in your car, or in the owner's manual: it should say 51R.
- The "R" means the terminals are reversed compared with the same number without R: the positive post is on the other side.
- Choose cold cranking amps (CCA) at least as high as the original, especially for cold winters.
- Group 51R has top posts: the new battery must match, and the hold-down must fit the box.
- Most stores take the old battery back for recycling, often against a core charge.
Group 51R batteries listed on eBay
Dimensions are the BCI maximums for the case, terminals excluded. Sources: Battery Council International, "BCI Group Numbers, Dimensional Specifications and Ratings" (batterycouncil.org), read October 15, 2026; Power Tool Insider, "Car Battery Group Size Chart" (powertoolsinsider.com), updated October 7, 2026.