17" or 18" is their a performance loss

[shrive81]

I have a 02 p5 and am looking to get new rims I was leaning towards the enkei RPM2 in the 17" at 16.9lbs they are rather low in wheight, would I loose much performance going with 18" that wheigh 18.9 lbs. I want the looks but if it is going to hurt performance much I rather go with what is best for performance.


PLEASE GIVE YOUR THOUGHTS<

 

[Black Majik MSP]

No offense, but if you have a P5, I don't think you need to worry too much about an extra 2lbs/wheel.

 

[CruzinAltitude]

(lol) black Majik, take it easy on us MP5 owners!

Actually, I would think the effect would be greater. Our cars have less HP, so wouldnt more weight effect the MP5 worse than the MSP. I know we are talking very minimally, but effected none the less.

 

[Reitrof]

Rim weight will make a huge impact. Go for the lightest rim you can get. CruzinAltitude is correct, weight will have a big impact. Try to stay within the weight of the regualr rims and tires. They weight 16lbs. You should also take into account what the tire weighs as well.

I had MP3 rims on for awhile but discovered my car was slower. Those rims weighed 22-23lbs.

I have Team Dynamics Pro Racer 1's in 17(from Rishie) and they weigh 15.8 lbs. The difference was amazing. My gas mileage also went up 1 MPG.

HTH

 

[CruzinAltitude]

The reality of the situation is I dont have the resources really upgrade the performance of my car. Becuase of that I bought the MSP racing harts based on looks alone. They weigh more than the factory rims and tires and I can feel it. Its not much, but I can feel a subtle diffrence in how quickly it accelerates.

 

[RyanJayG]

its not just the static weight of a wheel that matters, look at how far the mass is located from the center of the wheel. more times than not, you will be faster with a 15" wheel and tire that weighs 25 lbs, than an 17" that weighs the same

 

[CruzinAltitude]

Damn RyanJay, you one smart mo fo! I would have never thought about that, but now that you mention it it makes a whole hell of a lot of sense.

 

[Reitrof]

Hmm. I don't see that. If the tires are the same height be they 15 or 17 how does that change things?

Also you would loose some handling feel due to the larger sidewalls.

 

[CruzinAltitude]

The reason it made sense to me is the tire swing at my aunts house when I was a kid. If I twisted it all the way up and got on, then tucked my arms and legs in tight Id spin fast as hell (fun ride to!). If I needed to slow down I'd put my arms and legs out and BAM, just like hitting the brakes.

 

[RyanJayG]

Hmm. I don't see that. If the tires are the same height be they 15 or 17 how does that change things?

Also you would loose some handling feel due to the larger sidewalls.

The height matters not, if they are the same diameter, then there would be no difference to your spedometer and odometer.

BUT, have you ever seen the sidewall from the inside of a low profile tire? they are pretty beefy compared to a 50 + series tire. not to mention the actual rim is further from the center. This is a pretty heavy part of a wheel.

And, since force = mass x acceleration (F=MA)

accleration is higher the further you go from center
so, even an equal mass, but in a different location would require more force to move it

simple physics (thumb)

 

[RyanJayG]

The reason it made sense to me is the tire swing at my aunts house when I was a kid. If I twisted it all the way up and got on, then tucked my arms and legs in tight Id spin fast as hell (fun ride to!). If I needed to slow down I'd put my arms and legs out and BAM, just like hitting the brakes.

yup, Centripetal Force

 

[Reitrof]

Hmm. Still not sure you have a point if the wheels are the same height and same weight.

I think even if there was a difference it would be minimal. My point is the 15" rim diameter would not have the same handling as the 17" due to the smaller sidewall height.

I would take handling over the "maybe" minor acceleration.

 

[mazdamp3_18]

i beg to differ with a223818...

i have 15inch wheels with 205/50 / 15 and they handle and accelerate TONS better than my 17s

the car seems like a totally different car with the 15's ....which is why im downsizing to16's for my car....

i want lighter wheels... and i dont want to pay the HIGH prices of 17inch race tires all the time.... 15 and 16 race tires cost so much less than 17's .....

the mp3 wheels weigh i think 21-22 lbs... my 15's weigh 13lbs ...

i love the 15's but they dont look that great.. . and my speedo is way off but i dont really care about that since i use them for just racing...

 

[Reitrof]

mazdamp3_18
We are not talking about the cost. Sure you can get cheaper 15's but that's not the discussion.

And no wonder your 17's are slow, you are using heavy 17's(MP3 rims) with a tire that is much taller than the standard tire and your 15's are much smaller than the standard.

I'm talking about rims and tires that are the same height and weight, be they 15,16 or 17's.