1991 Pontiac Trans Sport — Base Model
The 1991 Pontiac Trans Sport Base Model 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.
205/70R14
| Section width | 205 mm |
|---|---|
| Aspect ratio (sidewall height) | 70% (143.5 mm) |
| Rim diameter | 14" |
| Overall tire diameter | ~25.3" |
| Revolutions per mile | ~797 |
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205/65R15
| Section width | 205 mm |
|---|---|
| Aspect ratio (sidewall height) | 65% (133.3 mm) |
| Rim diameter | 15" |
| Overall tire diameter | ~25.5" |
| Revolutions per mile | ~791 |
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What this size means for your Pontiac Trans Sport
On the 1991 Pontiac Trans Sport Base Model, the factory 205/70R14 measures about 25.3″ in overall diameter with a 143.5 mm (5.6″) sidewall, and completes roughly 797 revolutions per mile. Its 70-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 205/70R14 and 205/65R15 roll within 0.2″ (0.8%) 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.
Because the 1991 Pontiac Trans Sport 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.
Pontiac Trans Sport tire sizes by year
- 1999 Pontiac Trans Sport 205/70R15
- 1998 Pontiac Trans Sport 205/70R15
- 1997 Pontiac Trans Sport 205/70R15 / 215/70R15
- 1996 Pontiac Trans Sport 205/70R15
- 1995 Pontiac Trans Sport 205/70R15
- 1994 Pontiac Trans Sport 205/70R15
- 1993 Pontiac Trans Sport 205/70R15
- 1992 Pontiac Trans Sport 205/70R15
- 1990 Pontiac Trans Sport 205/70R14 / 195/70R15
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.