How much wheel plus sizing can I do before the ride is affected?

[nogard]

My mother-in-law is going to be getting an xB. I like that odd look, and I think is would be better with larger rims. I know it has the 15's stock. I would put snow tires on those. I want to go to a 16" or maybe a 17". I think the ride is already bouncy at 60-70 mph on the highway. She is 68 years old and currently drives a 2002 impala. The roads around here aren't the worst. Is she going to notice the difference if the summer rims where 16" what about 17"? She won't like it is the ride gets worse. Of course the tire size will be what it needs to be to keep the overall wheel size the same as stock.

Thanks.

[camryvibe]

Don't know how sensitive your MIL is to the ride quality, but if other things remain the same then it'll certainly be harsher with 16" wheels than with the stock 15's. Our Vibe/Matrix's came with 16" wheels and the ride is ok, but not as smooth as on our older Corolla that had smaller rims.

[HATEnFATE]

As soon as you decrease the amount of sidewall, which is what happens when you increase wheel size, the ride will start to become noticably more harsh. 16's.....maybe not too bad but if you think she'll notice any bit that makes it worse, I would just get a set of 15 inch alloys and leave it be.

just remember that when you're talking about ride, wheel size has nothing to do it, it's all about the aspect ratio of the tire. Most older cars had at least 65% A/R for the tire which means that the sidewall hight of the tire was as tall as 65% of the tread's width. Most new cars are around 55% and some even in the 40s.

The higher the ratio, the more bumps the tires can absorb. When you take that away, more and more of the small bumps are transmitted into the passenger cabin through the vehicles supension.

Another think you have to consider is how stiff is the vehicles factory suspension. Back in the day(5-10 years ago) most people wanted a smooth ride for thier cars. This meant soft shocks and higher profile tires. Now, people want that sporty feel when they buy a car which means stiffer shock and less tire sidewall which means a harsher ride for the MIL.

P.S. There's a LOT more to it then what I've explained, but we wont get into that.

[nogard]

Thanks for the feedback. I've bought wheels before and I do realize all that goes into it and I understand exactly what you are talking about with the aspect ratio and ride quality and suspension tuning. Not to mention the wheelbase of a vehicle will affect how it feels and at what speed you are doing most of your driving and how the chassis/suspension of the vehicle is tuned.

[jethro b]

17's would be the largest before ride quality gets affected. Proper size is 215/40/17 on a 7" wide wheel. Somewhere around 38-42 offset.
I'm on 18" TRDs and can tell a huge difference between my old 17"s.

[HATEnFATE]

Ride quality is affected as soon as you upsize to a 16 inch wheel and gets progessively worse as you increase wheel size and decrease tire sidewall.

[Zembonez]

I'm running 17s on my 09 xB and they are smooth as silk. While it is true that wheel size has an effect on ride quality, the tire you use has a ton to do with overall ride comfort. I'm running General UHPs which Tirerack.com rated at the top of the heap. Never bought a General tire in my life but I've come to trust Tirerack aftr buying half a dozen sets of tires based on their reviews.