> Tire/wheel Size Effect On Ride Quality And Handling

[beiuhiyf]

I've test driven and am considering a purchase of 3.8 Genesis with 17 inch wheels and 235/55R17 tires. The ride was great, the handling seemed fine.

Can someone comment on the likely difference there would be in ride quality and handling if the car was equipped instead with 18 inch wheels and 235/50R18 tires?

 

[Gurkha]

I've test driven and am considering a purchase of 3.8 Genesis with 17 inch wheels and 235/55R17 tires. The ride was great, the handling seemed fine.

Can someone comment on the likely difference there would be in ride quality and handling if the car was equipped instead with 18 inch wheels and 235/50R18 tires?

Original 17" tire size should be 225/55/17, not 235/55/17 as you stated.
I bought a used Genny that came with 215/55/17 tires (wrong size) mounted on winter rims and have the original Dunlops on 235/50/18 (original 18" wheels).
Speedometer reads faster in winter due to smaller tire size.
Although obviously not an apples to apples comparison, the 17" wheels are a softer ride.
The difference in sidewall height alone (55 vs 50) is a factor.

 

[Mark_888]

I've test driven and am considering a purchase of 3.8 Genesis with 17 inch wheels and 235/55R17 tires. The ride was great, the handling seemed fine.

Can someone comment on the likely difference there would be in ride quality and handling if the car was equipped instead with 18 inch wheels and 235/50R18 tires?

In general, 55 aspect ratio tires have a little more cushion against road imperfections than 50 aspect ratio tires, but the 50 aspect ratio tires have slightly better handling (partly because they are slightly wider). That is because the total tire diameter of both tires are (virtually) the same (assuming we are talking about the same car), so with a bigger wheel size, there is less tire distance between the wheel rim and the road on the 50 aspect ratio tire and it tends to be a little stiffer (all other things equal, such as same brand/model of tire).

You didn't say which model year (2011 or 2012). The 2012 has a more "comfortable" ride and probably doesn't need any additional cushion that the 55 aspect ratio tires provides. The 2011 might benefit more by the 55 aspect ratio tires of the 17" wheel.

Lastly, the base model comes with 17" Dunlop tires, which are stiffer than the 18" Michelins that come on the Premium and Tech Packages. That is just the difference between the design and rubber compounds used in the two different brands/model of tire.

 

[Darth V8er]

I have always upsized all of my tires on vehicles I have owned for the last 40 years. In the case of the 235/50/18s that are currently on my Genesis; when they wear out I will go to a 245/50/18. What you will get is a slightly wider and taller tire depending on the manufacturer, about .25-.50" in both height and width. This will in no way impact your MPH or cruise control. What it will do is give you a smoother ride, better handling, better tire longevity, better appearance in filling out the wheel well, better MPG (because Revs per mile are -9 over stock), same wheel/tire fitment, no perceptible loss of acceleration, no hassles from installing companys because of "these are not the original size tires" since they are an acceptible subsitute per their manuals, and all for only slightly more cost. To check out various tire manufacture's specifications, Tirerack.com is a great tool. On one of my vehicles, not a Genesis, I was able to go up from a 235 to a 255 with all of the previously mentioned benefits PLUS the tires lasted me 55,000 miles compared to 35k and 40k respectively on previous sets I had used.

 

[GLGar]

I also usually up the size on replacement tires and 245/50/18 is the size I plan to buy this time.. In addition to the benefits described I think the 245"s will improve the accuracy of the speedometer, odometer and fuel consumption read outs. Mine run about 3% on the optimistic side now.

 

[Darth V8er]

I obviously agree with your tire size choice and the reasons for it. I'd be interested in hearing which manufacturer you went with. Also, if your expectations were reached, that would be good to know too. I've only got 7,300 miles on my current, OEM, tires so I won't be shopping any time soon.

 

[GLGar]

I'm in about the same boat with only 10K miles but the wear rate is not looking very good. I keep checking prices at Tire Rack and Discount Direct.com and will probably pick the current least expensive V rated with the longest tread wear rating. Brand is not too important to me as I haven't had any really bad tires since Uni, Roy and Al tried to make radials back in the early 70's

 

[Darth V8er]

Wow, that's not good with so few miles. I've had good luck with Kumhos on two of my vehicles. They lasted forever and cost less than half what I paid for Michelin Sport A/S previously. I've heard from a number of people now that Hankook is another brand to check out.