Tire Upsizing Chart @ ModernOlds.net

Tire Upsizing Chart

***note: use this as a basic guide--- do all your research with multiple sources***
The chart at the bottom of the page directly relates to Oldsmobile Intrigue models, but could be adapted to any car with a 225/60/16 factory tire size

Anyone wanting to put a different size tire on their Intrigue for better performance needs to take into account the speedometer, vehicle computer, anti-lock brakes and traction control...If you put the wrong diameter tires on your vehicle, some of those functions may be affected... Generally, you can go plus or minus 10% in diameter from original and not have to worry about affecting your ABS, traction control or other computer functions drastically... Any change in diamter will affect your speedometer/odometer operations minimally, though you'd have to make a crazy change to make a drastic effect. If you're in doubt, please check with your dealer or tire shop.

Based on the O.E.M tire size of P225-60-R16 on an Olds Intrigue, you'll need to stick with the sizes below to stay close to the original overall outside tire diameter...Changes in width can produce tire rubbing. please chekc carefully... For instance, a tire size of P245/50/R16 will not rub on an Intrigue.

What the numbers mean...
Let's take a P225/60R/16 tire and break it down:

P: passenger car (LT would mean light duty truck)
225: the tire's tread section is 225mm wide (different manufacturers can vary a bit in true measurement

60: the tire's sidewall height from rim bead to tread is 60% of the tire's width

R: radial tire (if this was a bias-ply, there would be no "R" here of course)

16: the size of rim that the tire fits on in inches

other numbers on a tire treadwear rating: this is a three digit number that indicates the lifespan of the tire... the higher the number, the longer the tire will last.. usually, the higher the number, the harder the tire will ride as well. 300-400 is a long life tire.

temperature rating: usually rated A, B or C, this indicates how the tire holds up to high temps. A is best.

traction rating: usually rated A, B or C, this indicates how well the tire grips the road. A is best.

FOR 16 INCH WHEELS
P225-60-R16 (STOCK SIZE)
P235-60-R15
P245-55-R16
P265-50-R16

FOR 17 INCH WHEELS
P225-55-R17
P235-50-R17
P245-50-R17
P275-45-R17

FOR 18 INCH WHEELS
P225-50-R18
P235-45-R18
P245-45-R18
P275-40-R18

FOR 19 INCH WHEELS
P225-45-R19
P235-40-R19
P245-40-R19
P275-35-R19