I think 1151's steel wheels were standard 16's

 

Look for an old Saturn L200 with the basic rims. That's what I have as my winter wheels, with 195/65R15 tires. Very smooth but mushy handling; that's OK with me for the winter time, I tend to keep my speed down with those, keeps me from getting in trouble.

Good Luck.

Yves

 

Thanks Greybeard, yes, they are Standard 16's. HHR Stock LS wheels are 16"

 

The issues I see with 15" wheels and tires are...

1. A softer ride but less stability in cornering depending somewhat on the tire chosen and the final air pressures used.

Be aware that there are XL (Extra Load) tires available out there, and they would not be suitable for the softer ride.

2. Possible slightly reduced OA gas mileage due to additional friction from increased sidewall flexing etc. etc.

3. Possible limited availability in choices of decorative wheels and caps.

Unless you carry extra weight in the rear on a regular basis,
To start with, I would use the air pressures as follows,

Front cold 30
Rear cold 28

You can always pump them up, but you are after a softer ride ...right?

Stock air pressure on my 2011 is 30 front and rear but that takes into account that you may have 4 people in the car and there luggage too.

Other then more stability at higher speed there is no good reason to have 30/32 in the rears other then less rolling resistance.

Tire pressures are a trade off because of varying conditions.

Check to make sure the 15"wheel offset is the same as a stock wheel or you may need to re-align the front end.

SF