1985 Pontiac Grand Am — Coupe
The 1985 Pontiac Grand Am Coupe 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.
185/80R13
| Section width | 185 mm |
|---|---|
| Aspect ratio (sidewall height) | 80% (148 mm) |
| Rim diameter | 13" |
| Overall tire diameter | ~24.7" |
| Revolutions per mile | ~818 |
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215/60R14
| Section width | 215 mm |
|---|---|
| Aspect ratio (sidewall height) | 60% (129 mm) |
| Rim diameter | 14" |
| Overall tire diameter | ~24.2" |
| Revolutions per mile | ~835 |
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What this size means for your Pontiac Grand Am
On the 1985 Pontiac Grand Am Coupe, the factory 185/80R13 measures about 24.7″ in overall diameter with a 148 mm (5.8″) sidewall, and completes roughly 818 revolutions per mile. Its 80-series aspect ratio gives a tall sidewall of the kind used on trucks, SUVs, and older passenger cars, built for cushioning and load. In tire terms it is a small-diameter fitment typical of older or economy vehicles.
The 185/80R13 and 215/60R14 differ in both width and overall diameter (0.5″, 2.1%), which usually means a staggered front/rear setup — the two sizes are not interchangeable side to side, so match each to its correct axle.
Because the 1985 Pontiac Grand Am predates many current tire lines, confirm this size is still stocked before ordering — some vintage fitments are now served mainly by specialty and classic-car tire suppliers.
Other 1985 Pontiac Grand Am trims
- Sedan 185/80R13 / 215/60R14
Pontiac Grand Am tire sizes by year
- 2005 Pontiac Grand Am 225/50R16
- 2004 Pontiac Grand Am 225/50R16
- 2003 Pontiac Grand Am 225/50R16
- 2002 Pontiac Grand Am 225/50R16
- 2001 Pontiac Grand Am 225/50R16
- 2000 Pontiac Grand Am 225/50R16
- 1999 Pontiac Grand Am 225/50R16
- 1998 Pontiac Grand Am 195/70R14 / 195/65R15
- 1997 Pontiac Grand Am 195/70R14 / 195/65R15
- 1996 Pontiac Grand Am 195/70R14 / 195/65R15
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.