1998 Pontiac Firebird — Trans Am
The 1998 Pontiac Firebird Trans Am shipped with 2 different factory tire sizes, depending on the wheel package it left the factory with (this can also reflect a staggered front/rear setup). Check your tire sidewall or door placard to confirm which one applies to your vehicle.
This trim shipped with more than one tire size (staggered fitment, front/rear, or optional wheel package). Confirm which one matches your vehicle by checking your tire sidewall or door placard.
245/50R16
| Section width | 245 mm |
|---|---|
| Aspect ratio (sidewall height) | 50% (122.5 mm) |
| Rim diameter | 16" |
| Overall tire diameter | ~25.6" |
| Revolutions per mile | ~786 |
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275/40R17
| Section width | 275 mm |
|---|---|
| Aspect ratio (sidewall height) | 40% (110 mm) |
| Rim diameter | 17" |
| Overall tire diameter | ~25.7" |
| Revolutions per mile | ~786 |
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What this size means for your Pontiac Firebird
On the 1998 Pontiac Firebird Trans Am, the factory 245/50R16 measures about 25.6″ in overall diameter with a 122.5 mm (4.8″) sidewall, and completes roughly 786 revolutions per mile. Its 50-series aspect ratio gives a balanced everyday-passenger profile — enough sidewall to soak up road shock while keeping steering response crisp. In tire terms it is a passenger (P-metric / Euro-metric) size.
The 245/50R16 and 275/40R17 roll within 0.1″ (0.4%) of each other in overall diameter, so they are interchangeable from a speedometer standpoint — the second size is an optional wheel package rather than a different rolling size.
On a vehicle of this age, the Pontiac Firebird may have been refitted with a slightly different replacement size somewhere in its life, so check the current sidewall — not just the factory spec — before buying.
Other 1998 Pontiac Firebird trims
- Base Model 215/60R16 / 235/55R16
- Convertible 215/60R16 / 235/55R16
- Firehawk 275/40R17
- Formula 245/50R16 / 275/40R17
- Formula WS6 275/40R17
- Trans Am WS6 275/40R17
Pontiac Firebird tire sizes by year
- 2002 Pontiac Firebird 235/55R16
- 2001 Pontiac Firebird 215/60R16 / 235/55R16
- 2000 Pontiac Firebird 215/60R16 / 235/55R16
- 1999 Pontiac Firebird 215/60R16 / 235/55R16
- 1997 Pontiac Firebird 215/60R16 / 235/55R16
- 1996 Pontiac Firebird 215/60R16 / 235/55R16
- 1995 Pontiac Firebird 215/60R16 / 235/55R16
- 1994 Pontiac Firebird 215/60R16 / 235/55R16
- 1993 Pontiac Firebird 215/60R16 / 235/55R16
- 1992 Pontiac Firebird 215/65R15
How to read a tire size
A tire size like 225/45R17 breaks down into three parts:
the first number is the section width in millimeters
(the tire's width from sidewall to sidewall), the second is the
aspect ratio — the sidewall's height as a percentage of
that width — and the number after the "R" is the rim
diameter in inches. A letter prefix (P or LT) indicates
Passenger or Light Truck construction; its absence usually means
Euro-metric sizing.
Some trucks and off-road tires instead use "flotation" sizing, like
37X12.50R17 — here the numbers are the tire's overall
diameter and width in inches directly, with the rim diameter last.
Always verify against the tire information placard on your driver's-side door jamb or your owner's manual before purchasing — tire size can vary by factory option package even within the same trim.