Hey everyone. The new engine is in (carbed medium built 355 from a 305 tbi) and the low tread left on my rears is now more apparent than ever (real easy to spin when trying to launch hard). My next large step is to change my diff from it's econo-ratio to a nice 3.73.

My plan for traction is to simply figure out the widest rear wheels\tires I can fit with no major modification while keeping the fronts stock sized. Is this the right idea\attitude or am I making a mistake in my planning?

 

Is this street tires, drag radials, or slicks?

Are we talking at well prepped track, sugar watered track, or just street?

Street tires are designed to handle 40k mile tread life in multiple weather conditions not be ultra sticky for traction.

Shocks, springs, relocation brackets, sfcs, and etc will help to some degree.

Most people run 15x10s.

 

Yes and no.
Back in the '50s, racers discovered that wider tires seemed to help, and it looked meaner, so wide rears never went away. But back then, gaining traction was that plus clamping the leaf springs. Done.
But adding width without adding weight just shortens the length of the contact patch.
Do you need wide tires to hook? No. These days we have street rats out there, all over the country, who can run 9s on 275/60R15 M/T drag radials. Wide? Not really. M/T advertises the tread width at 8.8". And that's about right. Look at one mounted on a 15x10" rim.
If you want the look of wide tires, you can do 17x11s on the rear. 315/35R17s fit easily, and 335s aren't out of the question.
But if you want easy acceleration, choose some drag radials. You can fit 235/60R15s without even checking any of the clearances. And those 275/60R15s will work fine on stock 15x7" wheels.
But don't forget the LCARBs and some multi-adjustable shocks, and check the trailing arm bushings.

 

Don't forget a Posi. when changing gears. I have the Eaton and find its perfect for my street car. I have 255/60r15 in a "street" tire in the rear and can still get a fairly nice grab on launch. (Some spin but not real bad unless I want it to.)If I went to a sticky tire with the Eaton I have no doubt it would hook nicely. I'm not pushing allot of power with the 5.0 but feel its not bad for what it is, and the way I have it set up.

 

Yeah, posi will make more of a difference than tires if you don't already have it, but even posi is only good for about 10% traction increase, like the others said its more about properly set up suspension than tires when it comes to launching, not to say it doesn't help a little bit, just not the most important component.

 

put a 40lb bag of cement in each rear compartment corner.

u can go faster heavier if you can hook up.

 

my 275/60/15's started rubbing after my shocks got some wear to them

 

One of the things that will have to be addressed eventually is the topic of "can a 10 bolt survive behind a 355 with a T-5 trans and sticky tires." I have a built/up graded 10 bolt with 3.42 gears,28 spline Eaton Posi.,28 spline axles,and LPW Ultimate Support Cover but I am running a 5.0, auto. trans with street tires and get a fairly soft launch compared to 355,a manual trans.and sticky tires. Its a DD and that 10 bolt set up works for me. It may not last long behind the set up your running and some including myself will say get a 9in. or 12 bolt if your going to pound on it hard with sticky tires.