Performance change when going to 20 inch rims

[NorCal]

I've seen some passing comments on this topic but nothing specific. I'm guessing loss of performance would be due to greater rotating weight with the bigger rim. What I don't understand or know is if it is possible to get lighter rims and not lose anything. What about Magnum SRT-8 20 inch wheels and rubber? Are they using a lower performing wheel/tire just for looks? Are they likely to cause performance/ride comfort loss?

[done]

I've seen some passing comments on this topic but nothing specific. I'm guessing loss of performance would be due to greater rotating weight with the bigger rim. What I don't understand or know is if it is possible to get lighter rims and not lose anything. What about Magnum SRT-8 20 inch wheels and rubber? Are they using a lower performing wheel/tire just for looks? Are they likely to cause performance/ride comfort loss?

You have two issues.

One is unsprung weight. If your new tire and wheel combo weighs more you would have some loss of ride quality and handling performance when you really push out to the limits.

The second is rotating mass. I think this one is bogus. The absolute weight of the wheels is more important to acceleration. 40 or 50 pounds of extra weight might make .05 difference in the 1/4.

So, I think the DC engineers, at a minimum, validate using 20's. They went to a lot of trouble to upgrade to the SRT8. I don't think they would screw it up with the wheels they chose.

[deuceroadster2]

I'm not trying to hijack this thread, but how about braking performance or lack there of, when upgrading to 20" or larger rims? Anybody out there have any issues with poor braking after an upgrade?

[NorCal]

The bigger question is "What, if anything other than $2K+, am I giving up to have some cool looking 20 inch rims and tires?" What do I look for when selecting a wheel and tire package to keep performance and ride comfort maximized? I agree that the Magnum SRT-8 engineers wouldn't have downgraded performance to get a certain look. In some ways that makes it seem like the obvious choice for an upgrade - just get what they put on the SRT-8, if they are available. Are they?

[MAGNUM22]

I have 22" wheel with 265/35/22. I do notice a very slight difference from the stock wheels. Don't really feel a difference braking. You are goin to lose some performance by goin to the large rim. To put it simple large wheel take more to turn.

[MAGNUM22]

Yeah you can get STR8 wheels. For an arm and leg.

[SRT8AZ]

i am looking for srt8 wheels but the dealer wants a mint!

[obiwan]

I did not notice a change in performance when I installed my 20's but they are lighter than stock.

From what the parts guys at MPSC said, your not going to be able to use the SRT wheels due to some off set changes? Seems the SRT has different knuckles to accomidate the calipers and stiffer suspension.

[NorCal]

Too bad about the SRT 8 wheels that would have made things so simple plus I realy like the way they look.

What wheels do you have obiwan ?

[obiwan]

These, http://www.tirerack.com/wheels/DisplayWheel.jsp?wheelMake=EVO&wheelModel=Penza+5+SL&wheelFinish=Chrome+Plated

http://www.thegriffinclan.com/magnum/images/wilwood1_jpg.jpg

[NorCal]

very nice, thanks man

[Thrusst]

I just had the 20's that the dealer had installed traded back to the stock 18's. The car seems slightly quicker. The ride quality actually seems a little worse to me...The tire size on the 20's was 275 40 20 and on the 18's it's 225 60 18...

It seems to me like the car "pops" a little more when I take bumps in the road, but it seems noticeably quicker when I am on the gas.

I had the 20's taken off because I thought 2700 was too much - my boss is a former alloy wheel magnate and I am hoping he can find me a better deal. Besides, I have heard nothing but bad things about hankook tires and thought I could choose better rubber to do with.

[1sckmgnm]

I think you can feel a slight difference in performance from the 6 cyl with the 20s.I also feel a little further braking distance.but they look awesome

[Beast]

My 20s with 420s Nittos are the same height as stock. Had Eibach Springs also so handling improved for flatter turning. I'm having my car flashed on Monday for the larger wheels they have as a selection in Scan Star menue.( See other thread on that.)

[2ndmag]

You guys are thinking way too hard! The difference in performance is real and has little to do with weight and rolling mass etc., but has everything to do with gear ratios!
The size of the wheel and weight are not what count but more the circumference of the tire.
The circumference of the tire figures in as part of the gear ratio. It's exactly like changing sprockets on a bicycle. Just as increasing tire circumference makes for slower launches, moving to a smaller circumeference tire increases the gear ratio and makes for a faster launch. It has the same affect as changing rear-end gears.
This is why changing tire size affects your speedometer, odometer, abs, etc..
In order to move to 22" wheels you still need to keep the same circumference tire to maintain similar performance. Although, you probably will not like the ride.
I have 20" wheels with tires nearly identical in circumference to the original and have identical take-off performance, better handling, and reasonable ride quality.

[Beast]

Be sure to have the dealership Satr Scan the bigger tires. They have a menu of sizes to flash your car with.I have 255-45-20s.

[Dupie24]

My 20s with 420s Nittos are the same height as stock. Had Eibach Springs also so handling improved for flatter turning. I'm having my car flashed on Monday for the larger wheels they have as a selection in Scan Star menue.( See other thread on that.)If the tires/wheel combo ends up the same diameter, no change in gear ratio has occured, therefore no need to flash for larger tire, just my thoughts.

[apollo]

20 introduce longer braking and slower acceleration. The third factor is the tires. You could keep or reduce baking distance with a good tire. The problem is the lower sidewall, less flexibility. What you loose in braking and acceleration, you gain in cornering.

You need to decide what is important to you. I had my car since November of 04 and I am still putting my money in other mods but wheels and tires (and I got those hellish contis). I think I will just powdercoat the stock wheel on my RT and get a nice set of tires. Probably 1/3 the price and I will put the rest away for good breaks. I drive too much to f* with my breaking.

[moparman53]

I have 20" wheels with tires nearly identical in circumference to the original and have identical take-off performance, better handling, and reasonable ride quality.

That's what I was thinking of doing. What size 20's do you have?