I am looking to upgrade wheels and I was wondering if there is an advantage to 18" wheels that outweigh the added weight. I do about 4 track events and about 10 autocrosses a year. Any advice would be appreciated.

 

Advantages:
Bling
You can fit bigger brake rotors

Disadvantages:
Heavier
More expensive
Weaker
Rougher ride (assuming you keep same tire diameter)
More rotating mass
More unsprung weight
if you plan to keep your Evo in A Stock then bigger wheels are also illegal.

In short, unless you are going to fit larger brakes its better to stick with stock diameter wheels. The only reason road racers have bigger wheels is to use bigger brakes.

Here are two wheels that are stock-class legal, and much lighter than stock

Enkei RPF1
Kosei K1-TS

If you don't need stock size then the SSR Competition is lighter still.

-regards,
Alan

 

If you buy good quality 18 inch rims you do not have to worry about the weight, mass or unsprung weight. They will be more expensive however. My volks are much lighter and stronger than the stock Enkeis. The only disadvantage that is applicable above is the expensive part, but he is right there is no reason to buy 18's unless you want to look good or have larger brakes that require it.

 

But, size for size in the same construction a 17" is lighter than an 18". His question was what are the advantages of a larger wheel; my answer still stands.

 

The MR Forged BBS 17" are also a good option.

The other thing I have heard is that the 17" wheel is becoming less common as many manufacturers are moving to 18". This means that the tire manufacturers are making less and less tires for this wheel size, so rubber will become more expensive and less available.

If you can find something with a magnesium center then you are really doing well. Light tires really make a difference too -- Rotational mass is a killer. My Caterham wheels are only 3.2kg

That being said, I would still stay with the 17" wheels unless you need a brake upgrade.

 

The biggest advantage to 18" wheels is that you can run the 285/30R18 Hoosiers -- probably the best autoX tire available for the Evo.

Navid Kahangi (in Joe Harrison's Evo) won the ESP class at the ProSolo Finale in Topeka -- certainly the biggest autoX victory in the short history of Evo autoX in the US -- in September riding on just that wheel/tire combo.

Many of the top BMW M3s in Solo 2 autoX also run 18 inch wheels and the 285/30R18 tires.


That being said, unless you plan to run 285/30R18 race tires, don't bother with 18" wheels -- other than giving you access to these awesome tires, you won't see much benefit.

 

I am not looking for the bling factor, so it sounds like everyone agrees that I should stick with some light weight 17's. Are light weight rims like the SSR's or Volks safe for street driving or will the bend with the first pot hole?

 

the one nice thing about 18s for racing is that you have less sidewall so you will have less flex. however, I would still say your money is better spent in other areas such as brakes, tires, suspension etc...

 

This is not necessarily true as new tire technology is very good. Performance tires have a very stiff side wall, especially with something like the Hoosiers.

This is true if you have 85% aspect ratio on a 15" wheel in a tire that is designed for an Oldsmobile Cutlass but there is no noticeable improvement between a 17" and an 18".

 

Nope, try again.

Bigger wheels means bigger tires which means bigger grip and bigger heat dissipation. I don't know what kind of racing you do, but for most people that's pretty important.

 

Ummm.... I am not sure what you are talking about unless you are referring to width and even then it is not completely correct. This thread is about wheel "diameter", and in this situation, bigger is not always better -- Unless you are racing lawn tractors, and in that case I am out of my depth.

 

BLING BLING its all about the looks baby

for real the only benifit to going to a larger wheel is it looks better you can get lighter weight wheels in 17 than you can in 18 no matter what brand or what style if you compare equal wheels that are 17 to 18 18 will always be heavier.

 

Most EVO owners aren't into BLING. 17s are better on the track. Lighter, and a little more flex in the sidewall can be a good thing on the track.

The Kent Jordan / John Mueller EVO runs on Rays Gram Lights 17" x 8.5" with Hoosier 275/40(35?)/17s, and they do pretty good in that car on the track

 

Before anybody goes dismissing 18" wheels as BLING, be sure to do a bit of research...

Bob Tunnell, 12 time National autocross champion, runs 18" wheels on his M3. (http://www.bimmerhaus.com/raceprep/M3toBSP.html). Yes, he could run smaller, lighter wheels. No, he is not into BLING; he does what it takes to win championships. This is a guy who sometimes changes differentials depending on the course layout, and who has been known to set up a car with different spring rates on all four corners (and to win big with such a setup). If Tunnell runs 18" wheels, you can bet that he has tested them same-day back-to-back vs. 17" wheels and found the 18" wheels (with the low-profile tires) to be faster.

 

Read your own link. The reason he went with the 18" wheels was to take advantage of a particular tire -- as was already mentioned in this thread.

Most of the time an 18" wheel is bling, as Sentinal mentioned, as it is done for looks and not performance.