18"s too much for teener rims?, i want stiffffff sidewalls. Options

[Aaron Cox]

you will need lots of spacers... ($$$$$$$$$$$)

[nebreitling]

hell, spacers are the least of your worries. for that matter, so are wheels -- even though they are critical. i think a 180-200 mph 914 would be fabulous, and i think you could do it for under $100k if you did a majority of the labor.

anyway, i'm with mueller -- i'm sure you could get a 911 suspension working enough for 180 mph, but i'm not sure i'd want to be in the car. tube-frame, double-wishbone, aero developed, 600+hp might do it. at that point, you already built custom wheels.

until you're ready to pull the trigger at that level of development, i'd try to settle for for the more commonly available 5-lug 17" wheels. keep in mind that they will hurt your performance in all respects compared to a similar 15" wheel.

[DonTraver]

Don't want to rain on your parade, BUT. A lot of the sanctioning bodies (clubs) will not allow spacers on track cars. Autocross, no problem, time trials, club racing, a problem.

Just a bit more to investagate before you spend a lot of time, sweat, and money.

Good Luck, don

[monkei]

"until you're ready to pull the trigger at that level of development, i'd try to settle for for the more commonly available 5-lug 17" wheels. keep in mind that they will hurt your performance in all respects compared to a similar 15" wheel."

good to know about the spacer cost and rules. are you referring to 18s or 17s above? how would a 17 hurt performance over a 15 in any way other than weight? i would think the lower profile would allow for much better cornering...?

[Andyrew]

The added weight towards the outside of the wheel makes for more unsprung weight.. acutally its rotating mass.... When you add 30lbs to the vehicle its a whole different ball game then adding 30 lbs of rotating weight... Because now, the engine has to actually rotate that 30lbs extra, and not just push it...
Same goes for if you push the weight farther outwards.... Take a 2lb ball... attach to rope.. swing it at 6inches... then swing it at 12inches...

Figure a ~3% loss in hp per inch you go up in wheel diameter.
Same goes for cornering... car needs to jump over the weight hurdle to rotate and such.. also same for brakes... More stuff to stop...



FYI... rolled around with the 18's today.. AND 275 lb springs in the back... smooth ride. but I could feel just about everything... yet.. it wasnt unpleasant.. just noticable (very defined.. I could feel a crack in the pavement.. but it didnt kill my back or anything.)

[banksyinoz]

(IMG:style_emoticons/default/slap.gif) well im gonna change stud pattern its just too expensive to get wheels here if i redrill to 5x 114 (ford, toyota, mazda nissan) i can half the cost (IMG:style_emoticons/default/mueba.gif)
then get what i like in whatever offset (IMG:style_emoticons/default/clap56.gif)

icould have a set for every occasion eh (IMG:style_emoticons/default/av-943.gif)

22in giovanni chromies (pimp my ride style) (IMG:style_emoticons/default/aktion035.gif)
how slow would that be then (IMG:style_emoticons/default/dry.gif)

[groot]

For ride comfort the diameter has less to do with it than you may think. Tire construction has more of an influence on ride comfort.

You can get more lateral grip from a 15" tire in some circumstances. Bigger doesn't mean better, just bigger. And before you say, "He's doesn't know what he's talking about" please understand that I do this for a living.

I am a vehicle dynamics development engineer for the 2008 Focus; which includes handing, steering and ride development.

On the Focus, the 16" Pirelli P6 is more comfortable from a ride perspective than the fuel economy-minded 15" Hankook and I have data to prove that. The sidewalls on the 16" Pirelli are much stiffer than the 15" Hankook, but the larger tire rides better. We do make damper adjustments to accomodate the differences in the tires, and even after that, the 16" Pirelli is more comfortable than the 15" Hankook.... for the Focus.

[Dr. Roger]

keep in mind, i chose to put those wheels on knowing that i'm increasing unsprung weight but i'm probably pumping out >350HP, and i'll never go on the pro circuit road racing. maybe a little A/Xing but , God willing, a summer time daily street car... on steroids. =-) LOL

if i was running a 1.7/1.8/2.0 i wouldn't go larger than 17's and no wider than 10's in the rear.

if i was running a pumped up /6 i would get something fat and sticky.

[byndbad914]

here is a quick impression of a 914 at 180mph...

http://vehiclecraft.com/petitporsche.mpeg

Shove 525HP in and try going 140 in 3rd gear and see how stable that feels with stock suspension!! The front of my 914 sinks enough due to the wind pressure/lifting of the rear that the bump steer both front and rear f's with the toe enough the car wanders down the front straight at Willow Springs. That was with a spoiler and Sheridan body kit.

My tube car project is adding a wing, a front splitter and we are custom fabbing all the suspension mounting points to use Bilstein RSR struts and a 5-link rear to try and overcome all that crazy (read that as shitty) Porsche designed suspension/aero shape.

I am hopeful to just get near 160 without wandering the whole width of the track. 914s are NOT well designed from an aero standpoint. But with flares, wing, low stance and wide wheels, they look badass (IMG:style_emoticons/default/aktion035.gif)

As for wheels, go with what you like for looks for now. I wouldn't go over 17" as the tires get large in diameter. A decent 18x11 would run a 295mm tire. At a 35 series sidewall that tire would have an overall diam of 26", which is a big tire to fit under that car. I have 25.3" diam rear tires with a low car and that is a big ass tire overall diam wise IMO. You can get a 295 in 17" and have 25" diam which is mo' reasonable.

Check out Bill's car - similar HP to mine and same body kit, but his is actually done and painted and has 18" wheels. Looks pretty good. I like the look of a little more tire sidewall, but he definitely has the "rubberband" tire look that is really popular these days.

[Andyrew]

Im trying to go for 27in tires... The tires look TINY compared to the rims on my car right now.. (car is a little tall... but still) Lemme upload a pic.

[Dr. Roger]

hey andyrew,

love to see the pic of what your car currently looks like... =-)

[WRX914]

My 17's

[Brett W]

One thing to keep in mind when building a race car is the fender top /bottom clearence. When you put a tire that is 24-26in tall under our fenders and then lower the car you will hit the bottom side of the body under the strut mount. At that point you will have two options eliminate the strut or move the wheel further out.
By moving the wheel further out you will have problems with scrub radius and then you will have other issues. Issues you don't want to have at 200mph.

Look at a modern car and notice how much room there is inside of the fenderwell. The chassis are designed to compliment the much larger wheels available now days.

[turboman808]

Just bought some used 17 inch twist. ALso came with some old tires which is good so I can make sure and order the right size spacers.

[Andyrew]

I dont think 18's are too big...

Keep in mind my car needs to be lowered about 2 inches.

[lybones]

I know this is an old post but , I've got 18x9 and 18x10.5 on my teen. I used a 1.5" spacer for the front and a 1/8" spacer for the rear. check out pics on my v8 thread.

[JPB]

I deny all of your claims and reject this so call improvement. It is just wrong and all good looking bling bling and and , I don't accept it so I don't desire this kinda sweet sacrilege! (IMG:style_emoticons/default/smile.gif)

(IMG:style_emoticons/default/beer.gif) I hold a personal Jehad against this perversion of attractivness.

[Mr.C]

Here's a picture of the 18s I picked up for my project. They are going to be pretty much just for the street. I could of had a 87 928s, but I was two days shy. I'll settle for the wheels.
The 18s
Front 225/40/18
Rear 265/35/18

[rick 918-S]

Anyone have a source?

I wonder who could cut 18" Fuch wheels from a solid billet? You can have wheels made from 16' centers but they kind of look like the centers are too small. Or maybe just have custom centers with longer paddles made..... (IMG:style_emoticons/default/idea.gif)

[JPB]

Here's a picture of the 18s I picked up for my project. They are going to be pretty much just for the street. I could of had a 87 928s, but I was two days shy. I'll settle for the wheels.
The 18s
Front 225/40/18
Rear 265/35/18

I (IMG:style_emoticons/default/stromberg.gif) in your general direction as this Jehad continues to rebel against your sweet temptations. You have no pull against the faith of my resistance.

(IMG:style_emoticons/default/beer.gif) I return now to my rock and sand cave emanating holy golden rays of rightiousness!