2015 Buick Regal — GS
The 2015 Buick Regal GS 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.
245/40R19
| Section width | 245 mm |
|---|---|
| Aspect ratio (sidewall height) | 40% (98 mm) |
| Rim diameter | 19" |
| Overall tire diameter | ~26.7" |
| Revolutions per mile | ~755 |
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255/35R20
| Section width | 255 mm |
|---|---|
| Aspect ratio (sidewall height) | 35% (89.3 mm) |
| Rim diameter | 20" |
| Overall tire diameter | ~27" |
| Revolutions per mile | ~746 |
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What this size means for your Buick Regal
On the 2015 Buick Regal GS, the factory 245/40R19 measures about 26.7″ in overall diameter with a 98 mm (3.9″) sidewall, and completes roughly 755 revolutions per mile. Its 40-series aspect ratio gives a low-profile sidewall tuned for sharper handling, common on sport trims and larger-wheel packages. In tire terms it is a passenger (P-metric / Euro-metric) size.
The 245/40R19 and 255/35R20 roll within 0.3″ (1.1%) 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.
Other 2015 Buick Regal trims
- 2.0L Turbo 235/50R18 / 245/40R19
- Base Model 235/50R18
- Premium eAssist 235/50R17 / 235/50R18
Buick Regal tire sizes by year
- 2017 Buick Regal 235/50R18
- 2016 Buick Regal 235/50R18 / 245/40R19
- 2014 Buick Regal 235/50R18 / 245/40R19
- 2013 Buick Regal 235/50R18 / 245/40R19
- 2012 Buick Regal 235/50R18 / 245/40R19
- 2011 Buick Regal 235/50R18 / 245/40R19
- 2004 Buick Regal 225/60R16
- 2003 Buick Regal 225/60R16
- 2002 Buick Regal 225/60R16
- 2001 Buick Regal 225/60R16
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.