str8ner

I just acquired a 1973 rsr replica. 3.2, 300hp, 2200lbs. Anyone running something similar? Planning on running R6s Hoosiers, any size recommendation?

Thanks,

Stephan.

pu911rsr

Stephan,
You tire choice will be dictated by wheel diameter and width. Give us some more information and we can help.
Phil

MUSSBERGER

Pics,pics,pics................

rusnak

.....uh.

nope.

Would love to see the car though!

Bill Verburg

The original '73 RSR ran on 9 & 11x15 wheels w/ 230/600 & 260/600 tires

racer

sounds like 9's front and 11's rear? 245/315? 275front? But as mentioned, what size wheels do you already have?

A 3.2 with 300hp sure sounds a little high strung.. twin plug I assume?

MUSSBERGER

That thing will be a rocket on 15's as long as the brakes would fit.

str8ner

17 inch wheels, 9 front, 11 rear. Currently 245 front 315 rear. Serious understeer as is. Seems like a lot of tire for such a lite car with this kind of power. Was running the same tires on GT3. 100 more hp and 1,000 more pounds.
Anyone running a similar car?


Thanks,

Stephan

rusnak

You must have Popeye forearms.

strudel

I'm running the same on our '75 Carrera RS look race car w/3.4 325 h.p. The car weighs 2350 lbs. I run 245 fronts on 8.5 x 16's and 315 rears on 11x17's. I've also run 295/35/17's on the rear which work as well as the 315's. The advantage of the 295's would be less weight and wind resistance. I make a small rear sway bar adjustment between the tires.
The understeer can be cured by a good suspension set up. What are you currently running?

JackOlsen

I've run both 255/275 and 275/315. My wheels are 9.5x11x17. I have more weight and less power than you, which might explain why my best lap times are on the narrower 255/275 combination.

These pictures show the wider ones.





The problem you're going to have (probably) is how much tire you can fit in the front. My front flares are actually about an inch narrower than RSR flares, but my front suspension and steering components are not stock.

MUSSBERGER

I have the size on my SC. No understeer problems here. Rear bar too tight?
(2600 lbs and 180 hp)

race911

I settled on 245/45-16 and 315/35-17 on the old '74 3.5L widebody. No understeer, but if I didn't have some Fuchs-into-11's I probably would have stayed with the 275's in the back to eliminate some of the paint burnthrough at my desired ride height.

As mentioned above, your underlying suspension will dial in whatever you like. Many of us have run dramatically different setups and components. I ended up going back to rear torsion bars and a slightly larger rear stabilizer bar, combined with a relatively small front t-bar for my tracks. Others swore by coils on the rear.

SlickV8

[QUOTE=JackOlsen;7294272]I've run both 255/275 and 275/315. My wheels are 9.5x11x17. I have more weight and less power than you, which might explain why my best lap times are on the narrower 255/275 combination.

what profiles do you run on the different sizes? i'm building a car very similar to yours and have 17x9/11 wheels being made as we speak. I'm pretty well decided on compromise tyre sizes of 255/295 but i cant seem to clarify the correct [!?] profile difference. i.e 35 to 45 or 45 to 55 or 40 to 45????

How much better are your lap times on the thinner tyres by the way?
Thanks

JackOlsen

I don't think there are many options, on the profiles. On the 255/275 combo, both sets are 40 profile (for people unfamiliar with tire sizing: the profile is a percentage measurement of the width, so the sidewalls would measure 40% of 255mm in front and 40% of 275mm in back). On the 275/315 combo it's 40 on the 275 and 35 on the 315.