18 vs. 19" Handling

[RM7]

So maybe I know the answer already or should know it, but: 18 vs. 19 for handling/road course?

I am thinking that I might use my stinger on the nasty wet rainy days when we have autocross, vs. the dry days like today where I take my 800lb gorilla of a car, so the optimal setup would seem to be the smaller wheels for acceleration, braking, etc. Supposedly turn in is a little better with a bigger wheel with a stiffer sidewall (also only a 1" difference, which is pretty small), but the traction in the wet is better with a smaller wheel. I know with my other car, it's always the smallest wheels you can fit in there and over the brake calipers, for pretty much all forms of racing, but mainly I'm thinking autoX, small to medium courses.

Is there any reason to go to 19? If not, I will probably go for the wider 18" tires and then shop around for some slightly wider 18" rims to run 245 or 255. I'm not concerned about aesthetics, but if there's anything you think I'm missing or not considering, please let me know.

 

[turboAWD]

In general, I've heard that 18" tires are cheaper than 19". That's why I bought a set of 18" Enkei's, because I'm starting some HPDE days.

 

[RM7]

In general, I've heard that 18" tires are cheaper than 19". That's why I bought a set of 18" Enkei's, because I'm starting some HPDE days.

I buy 20s for my 1LE and I have a set of 19s for it. Yes, 19s are more expensive than 18s, but not by much. As every car under the sun now offers 20" as their top-end package, and some even bigger, the 19s have become damn near as cheap as 18s, compared to 20. Options in 19 are almost as good as 18, if not the same now. But I'm pretty sure that 18s should handle better than 19s.

 

[NS_Stinger]

I would think the lightest set of 18" wheels you can afford with some sticky tires would be your best bet.

 

[oddball]

A lighter wheel/tire package means lower rotating mass, which can mean faster acceleration and braking response. By a touch. *Usually* wheels weight a lot more than the tires, so a smaller wheel results in a lighter package. But the type of wheel matters a whole lot more. You can get light weight 20" wheels and heavy 18" wheels.

A shorter *tire* is equivalent to a lower rear gear. But that's the total tire height and has nothing to do with the wheel. Similarly, a taller tire is equivalent to a higher rear gear. So a short tire on a 19" wheel will accelerate faster than a tall tire on a 18" wheel, but the tall tire will have higher top speed. Usually the difference here is small, unless you're drag racing and talking about the differences between a 28" slick and a 33" slick.

Now, when it comes to cornering, especially hard cornering like autocross, sidewall rigidity matters a lot. That 1" is a huge difference in that case. This is where the OE setup with the 19" is better - a good tire, low sidewall, and section width on the narrow side for the rim. A taller sidewall will be more flexible, which will let the tire roll as you corner, which will make it break loose immediately. So you want a tire with a short and stiff sidewall. Different tires are made with different sidewall designs. I forget what it was, but the touring tire I ran on my last car was made with the outside sidewall stiff, and the inside sidewall flexible. This gave a softer ride than an all-stiff tire, but kept some of the better cornering characteristics.

 

[NS_Stinger]

One of the best low weight to cost ratio wheels I can think of for autocross is the Enkei RPF1, not sure if they will clear our brakes through.

 

[RM7]

Now, when it comes to cornering, especially hard cornering like autocross, sidewall rigidity matters a lot. That 1" is a huge difference in that case. This is where the OE setup with the 19" is better - a good tire, low sidewall, and section width on the narrow side for the rim. A taller sidewall will be more flexible, which will let the tire roll as you corner, which will make it break loose immediately. So you want a tire with a short and stiff sidewall. Different tires are made with different sidewall designs. I forget what it was, but the touring tire I ran on my last car was made with the outside sidewall stiff, and the inside sidewall flexible. This gave a softer ride than an all-stiff tire, but kept some of the better cornering characteristics.

Everything I've read about driving in the wet is opposite of that, while it does hold true for dry-driving.

 

[RogueIV]

One of the best low weight to cost ratio wheels I can think of for autocross is the Enkei RPF1, not sure if they will clear our brakes through.

Its a flat face wheel where they adjust the offset with the mounting pad surface so it should clear our brakes.

 

[G-189631]

Its a flat face wheel where they adjust the offset with the mounting pad surface so it should clear our brakes.

Very late to the chat. Just wanted to confirm that 18" RPF1s absolutely fit, as I've been running with a set on my 2019 Stinger GT AWD for years.
Im not a professional, but, a lot of the comments here about tires are as important as the wheels-- and the wheel weight and so on.

I came across this board because I just put 19" Konig Ampliforms (which, surprisingly, only weigh about 0.6 pounds more than my 18" RPF1s) yesterday and it's been---bizarre. For example-- I'm getting better gas mileage so far with the new wheels, so that's a plus (yea, I know that's counter-intuitive, but its crazy). However, the breaks feel like they lost some bite(even after warmed up. I know most people who drive my car typically hate how much the breaks bite, but I love it) the tires are holding more consistent air pressure, way waaaaay, less road noise, and overall it rides softer (like comort *actually** feels like comfort). Basically it feels more lux and less performance (which my adhdbrain cannot abide. Too much lux, means I'll get distracted). All that said-- I know *a lot* of that may have more to with the tires, but still RPF1s are with the right tires feel like a cheatcode for the Stinger handling. RPF1s have BF Good rich g-force Z-rated tires, where as the Königs came with Nokian Tyres. . . (That much to woe are only R rated. Who does that!?). Given Nokian tyres have a history of making excellent winter tires I was thinking they'd be grippier-- they are absolutely not. Experienced my first unintentional fishtail turing out of a parking lot and in good weather conditions, no less. (Had to work hard to drift with other set up-- this set up will drift-- but-- I'm concerned about how hard I can even push these. Plus I got this set mostly b.c it was an incredible deal, for pretty light weight 19s and they were far more aesthetically pleasing. Yea. So. Drifting with these might be the wisest idea.)

Anyway. I digress. As much as I really thought the 18in bright silver RPF1s looked somewhat out-of-place (ridiculous) on my Stinger, I already miss the way they ride/drive. Solid recommendation.

 

[socalvn]

I prefer my staggered 20s driving and performance wet or dry is amazing, I think the staggered affect really helps with performance, suspension also plays a critical role

 

[Volfy]

Very late to the chat. Just wanted to confirm that 18" RPF1s absolutely fit, as I've been running with a set on my 2019 Stinger GT AWD for years.
Im not a professional, but, a lot of the comments here about tires are as important as the wheels-- and the wheel weight and so on.

I came across this board because I just put 19" Konig Ampliforms (which, surprisingly, only weigh about 0.6 pounds more than my 18" RPF1s) yesterday and it's been---bizarre. For example-- I'm getting better gas mileage so far with the new wheels, so that's a plus (yea, I know that's counter-intuitive, but its crazy). However, the breaks feel like they lost some bite(even after warmed up. I know most people who drive my car typically hate how much the breaks bite, but I love it) the tires are holding more consistent air pressure, way waaaaay, less road noise, and overall it rides softer (like comort *actually** feels like comfort). Basically it feels more lux and less performance (which my adhdbrain cannot abide. Too much lux, means I'll get distracted). All that said-- I know *a lot* of that may have more to with the tires, but still RPF1s are with the right tires feel like a cheatcode for the Stinger handling. RPF1s have BF Good rich g-force Z-rated tires, where as the Königs came with Nokian Tyres. . . (That much to woe are only R rated. Who does that!?). Given Nokian tyres have a history of making excellent winter tires I was thinking they'd be grippier-- they are absolutely not. Experienced my first unintentional fishtail turing out of a parking lot and in good weather conditions, no less. (Had to work hard to drift with other set up-- this set up will drift-- but-- I'm concerned about how hard I can even push these. Plus I got this set mostly b.c it was an incredible deal, for pretty light weight 19s and they were far more aesthetically pleasing. Yea. So. Drifting with these might be the wisest idea.)

Anyway. I digress. As much as I really thought the 18in bright silver RPF1s looked somewhat out-of-place (ridiculous) on my Stinger, I already miss the way they ride/drive. Solid recommendation.

Sounds like the differences you felt had little to do with 18" vs. 19" wheels, and a whole lot more to do with the difference tires. Honestly, I've not come across any R-rated tires... ever! Snow tires? That's what they are known for. I had a set of Hakkapeliitta's back when I live up in the snow belt. Phenomenal Winter tires.

Both RPF1 and Ampliform are excellent wheels. Post up some pics. We have both, in 18x8.5, of course.

 

[7Andrei7]

Must be nice being able to install whatever tires you want on your car. The only reason I stuck to the 19" is that the 225 18" on the rear make the car look ridiculous.
Fat ass with tiny legs.