18" or 19"?

[kcbrown]

So in the "Centric and Stop Tech Rotors and Rust" thread, we've determined that you're almost certainly better off from a performance standpoint in going with 18" wheels instead of 19" wheels. And 18" seems to be a fairly popular size from what little reading I've done here.

All other things being equal, that makes sense. The 18" wheels are lighter and have a lower angular mass, and the same thing is almost certainly true for the wheel and tire combinations.

I'd want to run a square setup, which means using 10" rims with a stock suspension (said suspension to be modified later after I get some seat time).

The problem is that there seem to be many more available tire choices for a 19x10" rim than for an 18x10" one, at least when attempting to keep the overall diameter the same as the stock wheels and tires (255/40/19).

Tire Rack, for instance, shows 43 hits for 285/35/19 tires, 7 for 295/35/19, none for 305/35/19, and 24 for 305/30/19, for a total of 74 options. But it only shows 6 hits for 285/40/18, none for 295/40/19, none for 305/40/19, and 2 for 305/35/18, for a total of only 8 options.

There are a lot more tires for the 19x10" rims than for the 18x10" ones, and as time goes on, I expect to see more for the former than the latter.


As a result, between tire availability and improved caliper clearance, I'm awfully tempted to go with 19x10" rims for my first set of rims/tires.


Thoughts?


Also, would 305mm wide tires fit on 10" rims without rubbing under a mustang with a stock suspension? Or will coilovers be necessary for that to clear? What's the largest width tire that can safely be used for track and autocross duty on 10" rims?

 

[csamsh]

27" tall tires on 18" wheels look a little ridiculous and have too much sidewall. 285/35/18 or 295/35/18 is the perfect size.

ymmv

 

[Budwise]

I went with 19X9.5" on all four corners along with 285/35/19's all around and am satisfied. I was doing the same research and looking that you are now and finally settled on this setup. I wont have any track experience until October but I have high hopes that they'll do well.

 

[frank s]

If 18-inch rims disqualify so many tires, you'd certainly have more choices in 19s; however, are the best tires for your uses within the 18-inch possibilities? If so, then the absolute number of 19-inch tire choices is not really relevant if you prefer 18-inch wheels.

 

[kcbrown]

27" tall tires on 18" wheels look a little ridiculous and have too much sidewall. 285/35/18 or 295/35/18 is the perfect size.

ymmv

Does a 40% aspect ratio have a notable adverse effect on handling in this case?

The stock wheels and tires look to fill the fenders just right when the car is lowered a little, so in terms of appearance, my preference is to stick with that diameter.

My intent is not merely to drive the resulting setup on the track, but to also drive it on the street.

 

[kcbrown]

If 18-inch rims disqualify so many tires, you'd certainly have more choices in 19s; however, are the best tires for your uses within the 18-inch possibilities? If so, then the absolute number of 19-inch tire choices is not really relevant if you prefer 18-inch wheels.

That's true as far as it goes, but I'm looking at the trends as well. I do not wish to "commit" to 18 inch tires only to find that getting them in the sizes I want gets more difficult over time.

The overall trend in the industry seems to be towards larger rims, and has been for some time. As such, the larger selection of 19 inch tires at the widths and aspect ratios I'm interested in doesn't really surprise me all that much.

My point in raising that is not to illustrate that one size is actually better than another, only that I have concerns other than performance that may ultimately affect the decision of which rim size to go with.

 

[Budwise]

If you want to stay stock diameter then you're looking at a 285/40/18 which unfortunately the tire selection is really sucky for. This is exactly why I went 285/35/19 which there is a much better selection and I personally like the look better.

 

[zquez]

Taller sidewalls allows for more sidewall deflection. You'll find that shorter sidewall tires are more responsive.

My experience with 19's is that not only are the tires more expensive - albeit only marginally so - but the higher performance tires don't seem to come in the right sizes. 18s and 20s have more selection if you're trying to find wide tires. My 19's do fill the wheel well better than my 18's with slicks, but at some point you have to decide whether performance is the most important or looks. The only reason I'd go to a 19 from a performance standpoint is to fit the 13' Brembos.

 

[NDSP]

Kinda of along the lines of what zquez said. What is your end game? Performance or looks? Personally, I'm going to use 2 different sets of rims/tires. Because High Performance Summer tires that work well for autoX and track days will get used up entirely to fast for my 50 miles a day commute. Not to mention that those tires ( Hankook RS-3's, etc. ) don't come in 18/40/285, but they do in 18/35/285. I'm limited to 285 because of the class rules, so. Anyway, if your first priority is looks and you don't have a rule book your trying to fit with in, get what you think looks best and balance that with performance as best as you can. If performance is first priority, then 18's will get you the most options at the higher end performance tire spectrum. I've noticed when searching on tire rack that Rivals and RS-3's don't come up in most searches. These are the tires that most run in autoX street tire classes. Well at least in as far as I've been able to tell via my very informal interwebz searches.

 

[Norm Peterson]

Does a 40% aspect ratio have a notable adverse effect on handling in this case?

It will probably have a greater effect if the 10" wide wheel is at or toward the narrow end of the range of wheel widths for the tire size. When handling has top priority, you really want the wheels to be at least as wide as the "measuring width", and preferably out toward max recommended. Unless forced into it at a later date, I doubt that I'd go any wider than 285/xx on 18 x 10's even for purely street service (and I'm not completely sure I'd go with that much tire on 10's as a first combination). But that might be just me.

The stock wheels and tires look to fill the fenders just right when the car is lowered a little, so in terms of appearance, my preference is to stick with that diameter.

My intent is not merely to drive the resulting setup on the track, but to also drive it on the street.

There's a flip side to the appearance thing as well. If you are (or become) a semi-serious track junkie or autocrosser or simply end up as a hardcore cornering/handling fanatic it's easy to drive around all of the time on a wheel/tire setup that does not look like what most "everybody else" is running. People who don't care for what your occasional track day car looks like simply don't understand and probably never will, and their opinion suddenly carries a lot less weight. Those who do "get it" won't need it explained.


Norm