std vs. sport wheel size diff - important?

[wamanning]

the catera std was fitted w/ 225/55-16 rubber (~25.74" dia).

the catera sport was fitted w/ 235/45-17 rubber (~25.32" dia).

that's a 1.64% difference in diameter, with the sport being smaller.

anyone know if there were any differences in the shift-points, gearing, ABS/TC calibrations, or braking-system to account for the differences in wheel size?

reason i ask is that when going to "plus-size" wheels, it's recommended to stay w/in 3% of the original tire. for the catera, which size is considered the "original" to use as the baseline for new wheel sizes - the std or sport?

it makes quite a difference in the math and really limits what you can do using the sport size as the "original". but if there is no technical difference in the affected mechanics/electrics between the std and sport models, then using the std as the "original" in both cases gives you more flexibility in up-sizing your wheels.

[guardian]

Originally Posted by wamanning

the catera std was fitted w/ 225/55-16 rubber (~25.74" dia).

the catera sport was fitted w/ 235/45-17 rubber (~25.32" dia).

that's a 1.64% difference in diameter, with the sport being smaller.

anyone know if there were any differences in the shift-points, gearing, ABS/TC calibrations, or braking-system to account for the differences in wheel size?

reason i ask is that when going to "plus-size" wheels, it's recommended to stay w/in 3% of the original tire. for the catera, which size is considered the "original" to use as the baseline for new wheel sizes - the std or sport?

it makes quite a difference in the math and really limits what you can do using the sport size as the "original". but if there is no technical difference in the affected mechanics/electrics between the std and sport models, then using the std as the "original" in both cases gives you more flexibility in up-sizing your wheels.

Yours is one of the more interesting posts I have seen here recently. Am not aware of shift-point, gearing, ABS/TC calibration, or braking-system deltas between the sport and standard Cats. Also I confess I do not know the factory recommended inflations for these cars. This would impact rolling diameter.

My strong instinct would be for standard Catera owners to accept standard Cat wheels/tires as a baseline for their calculations. Likewise, Sport owners probably should use Sport wheels/tires as their baseline.

Good luck!

[wamanning]

Originally Posted by guardian

My strong instinct would be to accept the standard Cat wheels/tires as a baseline for your calculations.

that's where my mind's been heading, too...opens up more possiblities (mainly for winter rubber) on my sport's 17" wheels.

[guardian]

Wow!

Boy, you were too quick for me.

Sorry, but after you read it I re-thought this matter and edited my post.

[aldi]

The Omega/Catera was developed with 195/65R15. In Germany are the following sizes normally used.

17": 225/45, 235/45, 245/40, etc.
18": 225/40, 235/40, 245/35, 255/35, etc.