OT 2016 Toyota Avalon Rough Ride

[Wade Garrett]

I love my 2016 Toyota Avalon Limited....except for the rough ride. You can feel most every bump, expansion joint, pavement crack and manhole cover on the road. Even shallow potholes slam and are a teeth-jarring experience! The tires are inflated to the door sticker pressure and there's nothing wrong with the suspension.

I know Toyota gave this trim model a "sportier" suspension with

225/18/45 skinny tires on 18 inch wheels to improve handling- rather than go with the fatter 215/17/55 on 17 inch wheels on the lower trim models.

It's getting to be tire time and I wonder if it might be worth buying a tire/wheel package in the smaller size.

Would the taller 55 sidewalls absorb road bumps better? Any problems with transmission shift points, speedo readings, any of the electronics/gauge stuff, etc.?

[badgolferman]

When I bought my 2013 Lexus RX350 it came with 19" wheels. I made the dealership switch the wheels with another vehicle to the 18" wheels. I knew 19" tires are expensive and I wanted more air in them for a softer ride.

Does your Avalon come with suspension settings you can change? My 2004 Avalon was a very comfortable ride and we loved it. An Avalon is basically a Lexus ES and it should be a softer ride.

[micky]

The speedometer depends only on the circumference of the tire, which would be the same iiuc. The shift points also, I think.

any of the

18". 17". I remember when rims were 14" and 15" was someting special.

After 2 Catalinas, a Centurion, 3 LeBarons, and a Solara, I got Chrysler Sebring. Even though it wasn't built on the same chassis, I thought it woudl be like the LeBarons, but like you, I felt every little bump, bumps I couldn't even see on a street I'd driven on many times before without feeling any bumps. I'm not a race-car driver. I want to enjoy driving. Fortunately for me, the engine blew and I got another Solara.

It didn't even have 18" rims, but 17 or 16.

BTW, it's not just the amount air in the tires but the height of the sidewall. The higher the more there is to flex when going over a bump.

[Frank]

More air down there (volume in tire) the softer the ride.

[trader_4]

Things like that are OK if you buy it new or only a couple years old with warranty and only intend to keep the car during the warranty period or maybe a few years after. Outside that, those added complexities just become expensive things to fix when they break, unless you're DIY. Even then it can get pricey. Some are OK I guess because you don't necessarily need to use that part anymore if it goes kaput.

[trader_4]

There are online calculators available where you can put in the std tire size and whatever you want to compare it against and it will do the math and give you the speedometer difference. Generally you want to stay within a few percent and IMO having it read out on the high side is better to help avoid tickets.

[Jim Joyce]

I'm curious why the slightly wider tire is a "skinny" tire while the slightly narrower tire is a "fatter" tire, but I'll put that aside.

Doing the math, the 225/45-18 is approximately 659.7mm (25.9") tall when new, while the 215/55-17 is approximately 668.3mm (26.3") tall when new, with a difference of about 1.3% between the two. Sidewall heights are

101.25mm vs 118.25mm, respectively, but I don't think the harsh ride is due entirely to tire size. Tire construction could still play a role, with some tire models having a stiffer sidewall than others.

You say there's nothing wrong with the suspension, but if I needed to tame a harsh ride that's where I'd start, especially with the shocks. Spring rates could also be a contributor.

[Clare Snyder]

Definitely better ride, and NO change to any calibrations. The

215/55/17 will rie better. I would defintely be checking to see if a 16 inch rim will clear the brake calipers and if so go to a 215/ 65 16 or possibly even a 215/70) which will change the speedo calibration by a small amount but not cause any other issues)or 21

[Clare Snyder]

Fatter - not wider. More "meat" between the rim and the road

[dpb]

Way back last spring when Micky was obsessing over replacement tires I built a set of MATLAB functions to compare nominal dimensions from tire profile data-- those were

fnHSect=@(SW,AR) SW*AR/25.4/100; % Section Ht inches fnDrim=@(Drim,SW,AR) Drim+2*fnHSect(SW,AR) % Overall diameter (in)

where SW is standard width (mm) and AR the aspect ratio, Drim is nominal rim diameter (in)

For the above

there's 17% more section height for the 215/55 over the 225/45 but if you went with 225,55, that would be 22%--

Don't have a correlation for effective spring stiffness at hand, but that would be enough I'd think be noticeable in softness; just how much it'll affect the handling will depend on whether you really push the limits or not...

I really liked the stiffer suspension on the Chrysler 300M with the sport package option until moved back to KS on the dirt roads...then it was a tooth-rattling experience for sure. Plus, it had so little road clearance for mud sold it after a couple years. Anyways, back to the main thread,

Is only 1% difference overall diameter/same for circumference for calibration error...

if go back with 225.

Surprisingly, even the 16" w/ 65 ratio is about the same...

The section height portion change with the SW ratio compensates even more than the rim diameter change...