1st Gen. ITA tire/wheel size - Panasport

[cpa7man]

What tire and wheel size combo are most of you running? Please state offset of wheel also.
It seems most are running 13x7 (4" offset)Panasport with 225/50/13 Hoosier's.

Thanks for the input.

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Paul Pineider
ITA 05 (Soudiv)

[Scott Nutter]

Well, maybe the fast guys are running panasports$$. I've run 205/60's (Kumho and BFG) on both the stock wheels and Diamond Racing Wheels, 13x7 (4" offset), currently have a set of the Kumho Ecsta 700 215/50's that I think I ruined by running under-inflated.

What tire/wheel arrangement were you looking at?

[cpa7man]

Originally posted by Scott Nutter:
Well, maybe the fast guys are running panasports$$. I've run 205/60's (Kumho and BFG) on both the stock wheels and Diamond Racing Wheels, 13x7 (4" offset), currently have a set of the Kumho Ecsta 700 215/50's that I think I ruined by running under-inflated.

What tire/wheel arrangement were you looking at?

What tire inflation were you running? I run the stock wheel with Khumo Victoracers now. I'm looking at the Panasport 13x7 with Hoosier (on sale now) 225/50/13. I'm sick of being able to run as fast as any ITA car on the straights and losing seconds in the twisties.

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Paul Pineider
ITA 05 (Soudiv)

[This message has been edited by cpa7man (edited July 16, 2004).]

[mustanghammer]

I am using 13x7 Panasports - not sure of the backspace. They are a good lite weight wheel but they are a pain in the ass when it comes to tire mounting and dismounting. I used to bust tires at race tracks and always hated to see a setup Panasports. I usually service my own tires but when comes to mounting 225/45 Hoosiers I pay someone else to cuss my wheels.

I also have some Diamond 13x7 steel wheels for rain tires. They work okay, are not that much heavier than the Panasports and they are an excellent wheel to service. The negative with the Diamond wheel is that they are not hub-centric wheels and need to balanced using a fixture that locates the wheels by the lug holes. This information is on the Diamond wheels web site.

I have used stock wheels too and tires work better on 7" rims.

Scott



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Scott Peterson
KC Region
IT7 #17

[ddewhurst]

***They work okay, are not that much heavier than the Panasports***

Scott, my 13 x 7 x 4 inch backspace Panasports weigh 9 pounds. What is the weight of your Diamond 13 x 7 ?

Have Fun http://Forum.ImprovedTouring.com/it/wink.gif
David

[pgipson]

I use Panasports and Circle (aluminum) 13x7 with 4" backspacing on my Spec RX7. The steel Circles (Diamonds) that I have seen are quite a bit heavier than than the panasports or the aluminum Circles.

And there is little difference in price between the Panasports and Circle aluminums.

[Scott Nutter]

David my steel Diamond Racing Wheels are 13# each and only cost $60 each.

[cpa7man]

Thanks for the input.

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Paul Pineider
ITA 05 (Soudiv)

[ddewhurst]

Guys, I am aware that the Diamond's are heaver. When you forget about cost & someone says " not that much heavier than the Panasports" I need to say that's just like haveing a ITA car that weighs 44% more or 3427 pounds. I wish I could drive consistantly enough to say tha the 9 pound wheels were part of the equation.

Have Fun ;
David

[lateapex911]

I am with you Dave, wishing my driving would be capable enough to get teh most out of every tweak.

Wheels are an interesting thing. 4 or 5 pounds per wheel less to accelerate and brake is not inconsequential. I know there is software that can model the performance gain on certain cars, (not ours!), but any time we are talking about rotational weight, it is way more important than staic weight. Imagine losing 16 pounds off the flywheel...

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Jake Gulick
CarriageHouse Motorsports
ITA 57 RX-7
New England Region
[email protected]

paul, I have a set of panasports with 8 half life hoosiers im going to be selling next month, are you interested? make me an offer

Daryl

[Quickshoe]

Originally posted by ddewhurst:
...that's just like haveing a ITA car that weighs 44% more or 3427 pounds...

You don't really believe that, do you David? If so, you can put some 20# wheels on my car if you'll make your rx7 weigh 4000# and utilize panasports. Deal? http://Forum.ImprovedTouring.com/it/wink.gif


You need to factor in the weight of the entire assembly: wheel, tire, rotor, caliper, pads, bearings, ball joints, lug nuts, valve stem and half the weight of the LCA, brake line, steering arm and one end of the brake duct. The increase of 2-3 pounds of wheel weight isn't as huge as you imply. Yes, it makes a difference.

I had Diamonds when they offered the thin wall spun shell, with a thin center section which was not recommended for road racing, the 13 x 7 with 4" back space weighed less than 10#.

I bought 2 sets of Panasports for the FF, because the tires are extremely light, so the wheel is a bigger factor in the entire equation. The suspension components are light and the rear brakes are inboard.

[This message has been edited by Quickshoe (edited July 20, 2004).]

[ddewhurst]

" not that much heavier than the Panasports"

Quickshoe, strickly talking about difference between 13 pound Diamond & 9 pound Panasport including the thought process form above relative to weight. If 4 pounds don't matter here & there pretty soon the car is a way over weight. That was my only point.

Have Fun http://Forum.ImprovedTouring.com/it/wink.gif
David

[CaptainWho]

As some congressman from (I think) the 1950's once said: A billion here, a billion there. Pretty soon you're talking about _real_ money.

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Doug "Lefty" Franklin
NutDriver Racing (http://www.nutdriver.org)

[dyoungre]

One more point which wasn't brought up, with anecdotal evidence: Stiffness. I raced with Diamond wheels, and replaced them with Revolutions. I was able to take almost a full degree of static camber out of the front to get the same temperature profile I had with the steel wheels; Handling, lap times also improved more than I ever imagined with the change. The conclusion that I made from my experience is that the stiffness improvement is as significant as the 16 lb unsprung weight reduction (running a 4.44 gear, that would be about 4 lb flywheel reduction http://Forum.ImprovedTouring.com/it/wink.gif

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Dave Youngren
NER ITA RX7 #61

[Quickshoe]

Originally posted by ddewhurst:
Quickshoe, strickly talking about difference between 13 pound Diamond & 9 pound Panasport including the thought process form above relative to weight. If 4 pounds don't matter here & there pretty soon the car is a way over weight. That was my only point.



Gotcha--agree can't ignore weight everywhere or you will end up with a way overweight car. I crew chief in a series (SCCA Rally Grp 5) where there isn't a minimum weight. Every decision revolves around: how light can you make it, yet still be strong enough vs. how much extra will it cost for how much performance advantage?

[lateapex911]

Originally posted by dyoungre:
..... Stiffness. I raced with Diamond wheels, and replaced them with Revolutions. I was able to take almost a full degree of static camber out of the front to get the same temperature profile I had with the steel wheels; Handling, lap times also improved more than I ever imagined with the change. .... http://Forum.ImprovedTouring.com/it/wink.gif



THAT is interesting, but coming from you (An automotive engineer) it makes a lot of sense...



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Jake Gulick
CarriageHouse Motorsports
ITA 57 RX-7
New England Region
[email protected]

[Quickshoe]

Originally posted by dyoungre:
...as significant as the 16 lb unsprung weight reduction (running a 4.44 gear, that would be about 4 lb flywheel reduction http://Forum.ImprovedTouring.com/it/wink.gif



I am not an engineer (which may be obvious in about 1 minute of continued reading). Please give me a 2 cent education on how the 16# unsprung weight reduction translates to a 4 lb flywheel reduction.

It seems to me you utilized the rear gear ratio as a multiplier to calculate the relative energy required to turn the flywheel vs spin the wheels. However, aren't we talking about MOI (not unsprung weight) and have to factor in all the diameters and weight of the entire wheel assembly? Further you are taking mass from the center of the wheel, not the OD which has a smaller effect on the MOI.

Do I have it all wrong?

Great point about the stiffness of the wheels.

[dyoungre]

You are right, quickshoe, that unsprung weight isn't necessarily rotational inertia, and yes, the 'moment of inertia' of any 3D object takes the moment arm into account - but a flywheel and wheel are roughly similar - in fact, the moment of inertia for a wheel may be higher, as there is so much metal out at the rim. In any case, as Jake alluded to, further proof of my occupation would be the poor writing style, as I jumped from one topic to the next within a single sentence.

Wheels are rotating at a speed that is a ratio of your engine speed (which, of course, changes based on what gear you are in). If 4th gear is 1:1, then the rotational speed of your wheels is simply your engine speed divided by your final drive ratio (which in my case is close to 4). Since you have to accelerate all 4 wheels as you accelerate the car, the amount of energy you are putting into wheels would be similar to 16 lbs of rotating mass / speed ratio (4) - or the same as lightening a flywheel by 4 lbs. The comment was meant more to be a friendly 'dig' at Jake.... I'm sorry to have confused you.

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Dave Youngren
NER ITA RX7 #61

[Quickshoe]

Thanks Dave, I am always trying to learn. I posted the questions, risking sounding like I am always quick to pick apart someone's claim to the effectiveness of certain "must have" goodies.

For clarification, regarding the MOI of the wheel I meant that reducing the weight of the rim didn't have a huge affect (effect? I am never sure if I get those correct) on reducing the MOI of the assembly as the wheel is more towards the center. 12# wheel and 25# tire, vs. 9# wheel and 25# tire.

[lateapex911]

Originally posted by dyoungre:
...... The comment was meant more to be a friendly 'dig' at Jake.... I'm sorry to have confused you.....




That's why I said "imagine"! (When I started thinking about the math, I remembered the lawn I need to mow, the roof I need to install.....)

Besides, I know better than to be too specific with all the engineers lurking!


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Jake Gulick
CarriageHouse Motorsports
ITA 57 RX-7
New England Region
[email protected]

[ddewhurst]

Guys, the special thing about the people on this site is that they don't get their shorts all wadded up in a odd bundle.

No matter what the subject, it's always fun.

Thanks http://Forum.ImprovedTouring.com/it/wink.gif
David



[This message has been edited by ddewhurst (edited July 23, 2004).]

[dyoungre]

Quickshoe - true comment about the tire, and I think that points out one of the less mentioned aspects of Hoosiers versus some of the other brands; they tend to be lighter than others - less MOI. I haven't done any calculations, but I can't argue with my back to back experience. Good wheels did make more of a difference for me than just making the car look better!

...and nobody let Jake's humble nature fool you; he knows his science too!


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Dave Youngren
NER ITA RX7 #61

[benracin]

This is a great topic. I have always wondered how much of an effect my heavy arse steel wheels had on the performance of my car. So, the dumbed down version for us folks who changed majors after 2 years of engineering in college would be that science would indicate that heavy wheels vs. light wheels shouldn't make that large of a difference. Correct?

The point about the tire being a more critical part of the equation makes a lot of sense. I always though that trying to spin these heavy wheels up then slow them down again could be hard mechanical work.

Ben
ITA #33 Rx7 L-O-L

[cpa7man]

Originally posted by 7'sRracing:
paul, I have a set of panasports with 8 half life hoosiers im going to be selling next month, are you interested? make me an offer

Daryl

Send me an email, mine is [email protected]

Thanks!

Great discussion all. This is a great little forum!

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Paul Pineider
ITA 05 (Soudiv)

[This message has been edited by cpa7man (edited August 02, 2004).]

Hi Paul, you gave me a email adress that dosnt work.

I get my new house keys on aug 25th after moving from calif to wa state, ill get my racecar and wheels out of storage then.

wheels have 8 races on them and are still look new, im moving from ITA to E/P so ill be using 15" wheels.

Daryl Brightwell
Spokane WA

[cpa7man]

Originally posted by 7'sRracing:
Hi Paul, you gave me a email adress that dosnt work.

I get my new house keys on aug 25th after moving from calif to wa state, ill get my racecar and wheels out of storage then.

wheels have 8 races on them and are still look new, im moving from ITA to E/P so ill be using 15" wheels.

Daryl Brightwell
Spokane WA

Daryl, I put the right address [email protected] or at work [email protected]

That's funny because I just sent my check off to buy an e-prod car. I may keep the ITA car and rent it out. Still undecided. If I can afford it I still want the 13" wheels. My ITA car pulls like crazy but I get killed in the twisties. It would also help me sell the car with proper race wheels. What are you doing with your ITA car?

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Paul Pineider
ITA 05 (Soudiv)

WTB - Used transponder.

[This message has been edited by cpa7man (edited August 03, 2004).]