[dongo]

Hiya -

I have a 2019 328GT that came with 225/45R19 tires on all 4 wheels. I need to replace them soon and Tire Rack gives me the "Factory Option" for 225/50R18 as well, which are cheaper and higher UTQG (in general).

I'm not so concerned with the lower profile for aesthetics or whatever & would probably prefer the 18" tires, but another thread on the topic did nothing but confuse me about whether this is a slam dunk or not.

Can anyone tell me definitively whether the 18" wheels are okay?

thx!

[Billfitz]

18" wheels will give you a smoother, quieter ride and are less likely to suffer tire and/or wheel impact damage. Concern about pothole damage, and wanting the best ride possible, prompted me to avoid 18s and larger. I have 17s.

[dongo]

Originally Posted by Billfitz

18" wheels will give you a smoother, quieter ride and are less likely to suffer tire and/or wheel impact damage. Concern about pothole damage, and wanting the best ride possible, prompted me to avoid 18s and larger. I have 17s.

right, that's my preference - I want 18" tires, but my question is whether or not they will fit on my existing factory wheels that have the 19" tires.

[Billfitz]

No, only a 19 inch tire will fit on a 19 inch wheel. I'll spare you my posting the appropriate emoji.


I changed my mind.

[dongo]

Originally Posted by Billfitz

No, only a 19 inch tire will fit on a 19 inch wheel. I'll spare you my posting the appropriate emoji.


I changed my mind.

My bad, I can see now it was a stupid question.

[Ragnar The Redneck]

For those that are not born with the knowledge of all things automotive, here is a quick primer for tires:

Example size: P225/50R18

P = P-metric, or Passenger vehicle, metric size. Another common identifier used in place of P is LT, or Light Truck.

225 = Section width or tread width of the tire in millimeters, this measures across the tread.

50 = sidewall aspect ratio. This is a percentage of the section width of the tire and gives the measurement of the sidewall height. In this case, 50, would be 50% of 225mm, or 112.5mm. Other aspect ratios could be 60, 70, 35, 45, etc, and are not an exact measurement. A 225/60 tire would have a shorter sidewall than a 305/50 tire.

R = Internal tire construction. In this case, R would be a radial tire. Other designators would be RF for Run-Flat, or D for bias-ply (Diagonal).

18 = Wheel diameter. This indicates the diameter of the wheel that this tire will fit. If you have 17-inch wheels, this example tire would not fit.

There are some other descriptors after the initial size, 000X or 00x, where 000 or 00 is the load index of tire (the lower the number, the lower the weight the tire can safely hold), and x is the maximum speed rating of the tire (example, S = 112mph, H = 130mph).

[Oksamit78]

Originally Posted by dongo

Hiya -

I have a 2019 328GT that came with 225/45R19 tires on all 4 wheels.

thx!

Few things are confusing or peculiar:
1. 2019 328 GT? - I thought the last year production for 328 GT was 2016.
3. Although rare, but possible "square" tire set-up in 19" (all 4 tires the same). What rim style does you car have? Possible: 466, 598M, 673 or 674 if the rims are OEM.

Personally, in summer I run 19" 598M rims in staggered (225/45 fronts and 255/40 rears) and a separate set of 18" 281 rims, but "square" 245/50, in winter.