chrenan

I've been looking at 18x8 ET52 and 18x10 ET65 rims for my '87 951.

I know the hollow spoke turbo twists are comparable in weight to
the Design 90s my car has now. The solid spokes are much
heavier, I'm assuming this would be noticeable in terms of
the cars performance? Are the hollow spokes worth the extra cost?
Are the hollow spokes anymore fragile than the solid?

Thanks for any input guys.

samluke

If its a street car then it really doesn't matter. Fronts are 20.8lb versus 26 or so for solids. Rears are 24.5 versus 29 or so.

Both are equally strong. Hollows make for a great race wheel, light strong and easy to clean.

You won't notice any difference in performance.

ninefiveone

Weight matters more on the street where it impacts ride quality, steering feel, responsiveness off the line, and handling anytime the road isn't perfectly smooth like it is on the track.

DanR

this has not been my experience. I would say that for the majority of drivers they could not tell the difference!

951_RS

So, 27 lbs difference altogether, not to mention the wheels are un-sprung weight and also a rotational mass... That ends up being much more detrimental to performance than most realize.
A general rule of thumb is to double the wheel savings weight and that is how much dead weight on the car you'd have to remove to equal the savings of just lighter wheels. That is just for acceleration and doesn't even go into braking, suspension load, or cornering forces on the tires.

ninefiveone

There are definitely drivers that can't tell the difference. Doesn't change the fact that it is detrimental. Consider that a well sorted suspension has dampers tuned to the mass they are trying to control (wheels/tires). Also don't forget that the weight difference is multiplied by the control arm like a lever.

Basically there are 3 kinds of drivers:
- Those who notice
- Those who don't
- Those who pretend not to notice

5lbs is when people usually start to notice. Especially since it's a 16" to 17" switch and the tires end up being heavier as well. I would not be surprised to find that this setup is 7-10lbs heavier per corner.

Assuming that a fair number of people are into this car for it's handling, it would be a shame to purposefully reduce that.

ehall

Much ado about nothing. Get the wheels that you like best.

samluke

There is no questioning that the lighter the wheel/tire combination the better. There is no disputing the laws of physics.

I have tried them all, over the years ranging from some of the lightest to some of the heaviest (Mille Miglia Cup 3). Have various sets of wheel and have my lightest for races/qualifying.

I have never noticed any difference, nor have I ever seen anything in lap times I could directly attribute to wheel/tire weight. I have never noticed anything on the street either.

For track/racing, it makes sense to do everything you can to maximize performance (many small advantages barely noticeable on their own, can add up). For the street it really doesn't matter (IMO). For a Twin Turbo running the Autobahn at 150+, then I think I would want the hollows.

The hollows, both 996 and 997 are great wheels, I use them all the time. Having said that for most applications the solids are perfectly OK. I have a 996 with factory twist solids. It performs just fine and I am not about to change them.

One of the heaviset wheels out there are the RUF 5 spoke at over 30lbs, and you see them on some pretty exotic cars.

As Ehall says, buy what you like/can afford.

ninefiveone

I agree...buy what you like. Just make an educated choice.

The folks who say it doesn't matter just haven't ridden in a 944 that rides well on the street and assume the impact harshness is inherent to the car. It's not.

Van

You have to add:
-Those who don't notice, but pretend to!

ninefiveone

Also true!

951_RS

A lot of people pay a lot of money just to lose a few pounds off their car constructing carbon fiber bits, etc. These lighter wheels probably don't cost so much more that it wouldn't be worth it.

ehall

Pretty much everyone is correct, that has responded. The reality is that you're driving a car on the street strictly. Weight, as I'm sure you know, is the enemy of speed and racer's need speed. On the street, as long as the wheels are of good quality, this issue is meaningless, within reason. Unless you have a LOT of racing time, or go with a vastly larger tire/wheel combo, using small stiff sidewalls, you are highly unlikely to notice a difference. Now if you have a crappy alignment, big heavier wheels will make the ride really bad, by comparison to smaller lighter wheels.
Make sure the wheels are as perfect as possible and get the car aligned at the same time. You'll be quite happy.

951Saga

^^^ This is what you’ll notice most of all changing from the D90’s.

Here is a cool Hollow Spoke prototype photo and link to page, www.sportauto.ee...it's down the page a bit right after pics of the first Porsche.

chrenan

Thanks for all the input guys, much appreciated, I decided to go
with the hollow spoke wheels. Its not really a track car, apart
from one very fast autoX course per month with the local PCA, and
I doubt I'm a good enough driver to notice the weight difference.
However, I figure if I ever want to sell them later, the hollow
spokes will move quicker, and when I look at them on my car, I
Won't be thinking "I should have got the hollow spokes".

Now to figure out tire sizes...in this new thread...

https://rennlist.com/forums/944-turb...8x10-et65.html