If you have seen this message before, it was suggested that I post this message here.

I am building a lightweight street legal sports car (including frame and body). It will be a 1600 lb 2 seater RWD speedster (mid engine) with full independant suspension and discs all around.

To start I want to select tires, wheels and hubs. I am looking for suggestions for common tires, wheels and hubs that would be lightweight, good performance, readily available
and "relatively" inexpensive.

Looking at the SCCA Spec Ford racer (which is 1600lbs) it uses:

Rims:
13 inches x 5.5 inches
13 inches x 7 inches

Tires:
185/60-13 for the front
205/60-13 for the rear

The hubs have 9" rotors.


Since the car will look similar to the Opel Eco Speedster, their wheels are:
175/55 R 17


I have gone through most everyone web site, worked with a few racers (SCCA Spec Ford, and Porsche), have worked with a number of builders and read all the suggested reading. I want to get some other opinions.

Any suggestions are greatly appreciated.


thanks

d1

Some of us USA builders on this forum are building cars very similar to what you describe. Look for 'Meerkat', 'Kimini' and 'La Bala'.

Tire/Wheel and upright choice is the correct start point.

If you start with a front suspension design similar in configuration to the Locost, that would be a good start. Obviously your upright choice makes a big difference in the actual placement of the pivots.

The available US alternative uprights are - Spitfire, Miata, S-10, Pinto... Some of us have decided to build a ball joint adapter for mcPhereson strut style uprights. I have seen Formula Fords using this method both front and rear. Alan B. (meerkat) used this method, and his work was inspirational for my doing a similar design.

Lightweight to me means 13" wheels, but if you want to drive it on the street it really limits your tire selection. I'm going to use Hoosiers, but tire life won't be great. The saving grace will be that your car is light.

13" wheels will also limit you to 10" brakes if that's an issue to you.

On the issue of uprights, keep in mind you can always cut down MacPherson struts and attach an a-arm to the top. Some people even use the strut assemblies where the shock tube bolts on, replacing that with a pivot to the upper a-arm.

Thanks for the feedback. I want to avoid struts and use A-arms to keep roll center low.

I spoke with a few racers and they suggested using Honda CRX or Acura hubs and wheels, as they are often used in racing, so lots of high performance parts available for moderate prices.

Thoughts on using this combination?

thanks
d1

Using modified, cut-down struts, you can put the roll center anywhere you want - it's what I used.

The Honda or Acura uprights I'm aware of are about 18-24" tall so I'm not sure that's going to be a plug-and-play solution.

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Tire/Wheel and upright choice is the correct start point.

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Originally posted by RallyHarry

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Tire/Wheel and upright choice is the correct start point.

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... or the windscreen as it's impossible to find one that fits your "perfect" design.

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Totally off topic as usual but...

There are a number of "kits" that use custom poly carbonate windshields.

Does anyone know what the cost is and what the minimum run on something like that would be?

Good point about the windshield! While it's not an issue for me, I do remember bringing it up when someone suggested I make a "wide-body" Mini and have no fender flares. Where would I get the windshield from? Never came up with an answer so the wide-body idea was discarded.

About "plastic" windshields/windscreens, there are a couple places that sell pre-formed sets for a few cars, almost always Hondas, for dragracing... I don't really recommend it for the street, especially the windshield. Even the scratch resistant version will quickly scratch if you have wipers... and it's expensive stuff, around $100 for a 2x4 ft sheet. And AFAIK it won't be legal in many areas.