planning to upgrade my stock 16" with 18". my new tire size will be 225/40/18 front and 255/35/18 rear. will i feel a drastic loss of power due to the larger wheel??

thanks...et

 

I would say yes you will feel a loss in "pick up" Im using nocab 72,s Borbet 18s great looking but 25 lbs each and I guess a loss of about 30hp!!.( i dynoed today)
The way around that is to buy a light rim, expensive but in my opinion worth it, the ce 28n by Volk is very light for a 18 ,within half a pound of the stock 16s so that would be a good choice,check with Rishie on the forum.

 

Damnit, when did this happen!? I want them wheels back!

While the wheels are not the lightest available, its the Kumho Ecsta Supras on there. These tires are among the heaviest for a given size, I found out after doing some research recently.

Suppposedly Toyo T1S and Pirelli P7000s are among the lightest, and switching to these may save 4-5lbs off each corner.

 

Sport Compact Car did a comparison with 16/17/18 wheel/tire fitments. The short answer is 16s were the fastest, 18s were the slowest, 17s were the best compromise between stick and speed. 18s had the same effect as adding 100-lbs of ballast to the car...yup that's alot!

 

I read that article too in Compact car too,....doesnt seem to be stopping me from wanting 18s though?sheesh I should get 14s and stomp everybody!!!!

 

i dont see how that test in SCC can be accurate.... it all depends on the wheel they were using.... some 18" wheels are lighter than some 16" wheels.... so they cant generalize and say that 16s will always be faster than 18s...

 

They took the same rims in 16,17 and 18 inch sizes really to demonstrate the different characteristics around a track.

 

PM forum member OSdesigns, he has an extensive knowledge of how wheel weights an effect performance (since he has a lot of customers who actually road race)

 

Trying to figure out the cost in performance caused by heavier tires and rims..
Stock rims are ~16 lbs
Most aftermarket rims (plus 1 or 2) 22-26 lbs..plus the weight of a larger tire..

rimshttp://findarticles.com/cf_dls/m0BUX/12_30/57160084/p1/article.jhtml?term=

 

You always give up something to get something else...it's the law of conservation of matter...a universal axiom...

The challenge lies in what you're willing to give up, to get what you want...what's a fair trade...?

To get more stick, and better handling feel, the consensus among us FD racing enthusiasts has been to go with 9 x 17 with 255/40-17 for both road AND track use. This wheel/tire combo affords the best stick/handling feel in exchange for a little extra weight at each corner.

An SSR Integral A2 in 9 x 17 weighs 19 lbs each wheel. If you put a 245/40-17 Hoosier R3S03 on that wheel, the total weight is 39 lbs...same as the stock 8 x 16-inch--225/50-16 combo.

If you want to take on a little more weight in exchange for a just a bit more grip/handling, you'll go with 10 x 18 with 285/30-18s at each corner.

A CCW 10 x 18 tips the scale at 22 lbs each. Mount a 285/30-18 Hoosier R3S03, and the total weight is 43 lbs...4 lbs more than stock, but at least 2-inches more width all the way around...

Are these fair trade-offs?

Depends on what you plan to use your car for...

For road course track racing...definitely a fair trade-off...

For straight-line drag racing...you're better off staying with stock 8 x 16s and slapping on some fat Mickey Thompson drag slicks!

 

SleepR1,

I'm only going from memory, but wasn't the SCC article about handling? B69ET is asking if the 18's will cause a noticable effect on his power. I think he wants to know if he'll feel his car being slower. My personal opinion is he wont. And it certainly won't show up as a loss on a dyno, unless it is inertial and he performs the run in a very low gear (which is not normal).

Wade

 

Very good outlook on the situation. I think when I do finaly get rims I will go for function more than form. The CCWs seem to be a trade off of both, great wheels. Untill then the stock powdercoated will do great.

 

Wade, call me freaky...or perhaps, it's all in my head, but I felt a power loss in acceleration with the 9 x 17 IA2s/255/40-17 AVS I's all around vs the 8 x 16 IA2s/225/50-16 P-Zeros!

 

Before I put on the 18"s, i could keep with Nocab,s rexy 315 to 320 at the wheels with his 18" SSR intergrals
(20 1bs)
me with stock 16 inchers (about 16 1bs) and less mods, 285 at the wheels.
Now with 18s on and about 9 extra 1bs at each corner he pulls away easily,so i would need 30 extra hp. just to keep up!

 

I got some lightweight 18's on my ride. 19.8lbs and they dont look too bad. I have the Konig Toxxins on my TII. I actually have better acceleration IMO from stock. Have a look http://home.insightbb.com/~hellbird.79/NewTII.htm

Hope this helps

 

Daniel,

hahah, mp5 is just "borrowing" those wheels, he is local to me and wanted to try a set of 18's out before he dropped the coin on his own.

mp5 will need alot more than a light set of wheels to keep up when I start putting down 380rwhp on my stock engine/stock twins @ 12psi!

K

 

SleepR1,

It was probably "in your head." I'm assured by an engineer that adding 10 lbs to each wheel would be the same as reducing power about 2%. So in a 300rwhp car, it'd cost about 6rwhp. Also, the effect is even less as speed increases and drag comes in to play. Maybe it was cooler outside the day before you installed the bigger wheels, who knows.

mp5,

The differences in acceleration you've seen are due to something else.


Heavy wheels might make the car feel heavier, but they won't affect acceleration noticably unless they are extremely heavy.

Wade

 

I've switched back and forth between my set of SSR Integrals 18x9 w/ Toyo Proxy T1-S's and my set of Borbet's TD's 18x9 with Kuhmo Escta 712's.

The Borbet + Kuhmo combo is probably 10lb heavier/weheel than the SSR/Toyo combo. I can DEFINATELY feel the difference off the line and around corners. The car feels like it has "weights" on each corner of the car when I turn corners with the Borbets, with the SSR's the car feels much closer to stock, just much much firmer and tight in the corners.

K

Wow, I just re-read that and damn am I having composing problems this morning...

 

I'm glad I'm not the only one who can tell the difference

The Toyo Proxes T1-Ses are very light tires too, so that lightness adds to the near-stock feel of the SSR Integral A2s (9 x 18)

BTW, nocab72, I'll be in your neck of the woods next week at TracQuest's Mid Ohio event Tues/Wed August 13/14...you should come up from Columbus and visit. There will be at least 3 red FD Rx7s, plus one '86 FC from Indy and Louisville, going at it with BMWs, Porsches, C5s, and Vipers

 

nocab,

I'm not debating that heavier wheels might be noticable in the way the suspension feels, a lot of people make that comment. Maybe this is why some people feel that heavier wheels really slowed their car down, just the "feel" of the handling. But in reality, it won't slow you down in a straight line, negligible change in acceleration. That's what the original question in this thread was about.

Wade

 

Hey, I'd like to do that!!! How late into the evening do the events run? I could cruise up after work, only about an hour away from me!

k

 

Here's the schedule

http://www.tracquest.com/MidOhio/MidOhioAug02.htm

 

Looks like I wouldn't get to see any racing after work, maybe I'll just have to take a day off! whoohooo!

K

 

You might as well be participant then. Event organizer, Todd Serota, is down on participants, and could use more attendees to keep him from losing his shirt. Mid Ohio's expensive to rent, you know!

You can attend for one day for $250. You'll get the same amount of track time as you would with the Mid-Ohio Region PCA (~3 hours per day) drivers education weekend.

FWIW, I'm one of the instructors...I'll have you flying around Mid Ohio by lunchtime

Give Todd Serota a call. You can fax your application and pay with a credit card. Tell him I referred you.

Hope to see your silver bullet. Look for three red FDs under a blue canopy, next to a black 28-foot enclosed trailer. That'll be our group. My red FD will have "I-73" with Hoosier decals on it

See you then (I hope).

 

I would ALMOST cancel vacation to attend the event. It's just a FREE vacation that makes it too hard to cancel it.

I am bumming. Nocab, you better go so I can live out the details!