Strange 12 bolt 3" narrowed ?
If you read the original question you would have noted that the car is going to be a race only car. She has also been following some of my threads in the LT1 section. The 9" x 30" radial is a far superior tire than most of what you experts are running. Even a stock internal car will work well with them. To get the most out of them you have to choose the right gear set. The 1982-92 rear is a direct bolt in. It is narrower, and will allow a lot of wheel choices. LCA brackets are only good to correct suspension geometry. They are not a mandatory addition to the rear suspension. If set up incorrectly they will put the suspension in a bind.
Like David said, if you don't make the power or have a bigger gear, it will bog the car down. And there is no cost to narrow .5" or 5". Why not reduce the weight and run a bigger dish than "settling" on a 3rd gen rear end?
Bottom line is the 30x9 might work for you and the other stock eliminator guys, but unless she sets the car up like that, there are better options out there.
Anyone that tells you a 275 60 15 on a 15x10 takes work to fit doesn't know what they are talking about. It means they didn't order the right offset rim, PERIOD. I have a 275 60 15 on my car and there is plenty of room inside and out.
Buy the 15x10 rims and mount the 275 60 15's on them then set them in the wheel well and center the rim so it clears just right, then measure between the two rims and order your rear end that width. Don't forget to compensate for brake rotor thickness.
As far as what people run on the 275 60 15 on a 15x10 they have run in the 7's, and a personal friend of mine has run 8.30's on the same tire and rim set up.
Buy the 15x10 rims and mount the 275 60 15's on them then set them in the wheel well and center the rim so it clears just right, then measure between the two rims and order your rear end that width. Don't forget to compensate for brake rotor thickness.
As far as what people run on the 275 60 15 on a 15x10 they have run in the 7's, and a personal friend of mine has run 8.30's on the same tire and rim set up.
Anyone that tells a person who runs 13's to put a big tire on their car needs to put to big of a tire on their car and see what happens.........
You DO NOT NEED A 15X10 ON A 13 SEC CAR PERIOD!!!!!!!!!
Look at th 8.5 class guys and see how fast they are.
Look at Outlaw 10.5, they are on a true 10.5 and in the 6's!!!!!!!!!! THATS SCARY!
If I was this guy I would get a light factory wheel and throw a drag radial on it (if rules allow). Would be no problem at leat into the 11's with suspension.
If he wanted to go 10's or faster then I would look at a 15X10 then.
My car went 11.1 on a 28X8.5 keep in mind its a nitrous car and 3.73 gear. Spun going 10.4@136 factory boxed LCA's, non adj torque arm and PHR, no rear sway bar, factory looking springs and shocks. It would have been hooking this summer if I would not have hurt the motor.
You don't need a big tire, I am only going to a 15X10 for saftey because I will be making more power next year..... Tire height is based more on trap RPM then traction. Width is based on traction and HP alone, you want to run the smallest tire and wheel that you can and still hook.
Matt's car and mine are both slow
, you could push mine right now, thats about it 
And anyone that tells you a 275 60 15 on a 15x10 rim fits without any problems has thier tires sticking out too far.
It fit fine on a stock width rear with 5.5 BS, stuck outside the wheelwell pretty far but fit fine inside. Installed the 12 bolt shortened 2.5 inches on each side and all hell broke loose.
Anyone that doesn't believe me is welcome to come to my house and stick thier head up my ***, well my cars *** and take a look around and tell me they would have fit without all the work I did.
To make a broad generalization like "wrong BS, period" is just wrong. It depends on the look your going for as well as performance.
And yes I run a 275 60 15 with a 15x10 rim on a 13 second "slow" car.
Guess what? I don't have to burn the tire to the ground to get it to hook. Saves a lot of wear and tear on my rear brakes (no line lock), drivetrain, and wallet.
It fit fine on a stock width rear with 5.5 BS, stuck outside the wheelwell pretty far but fit fine inside. Installed the 12 bolt shortened 2.5 inches on each side and all hell broke loose.
Anyone that doesn't believe me is welcome to come to my house and stick thier head up my ***, well my cars *** and take a look around and tell me they would have fit without all the work I did.
To make a broad generalization like "wrong BS, period" is just wrong. It depends on the look your going for as well as performance.
And yes I run a 275 60 15 with a 15x10 rim on a 13 second "slow" car.
Guess what? I don't have to burn the tire to the ground to get it to hook. Saves a lot of wear and tear on my rear brakes (no line lock), drivetrain, and wallet.
On the motor I had my car hooking on 20ish PSI, at night, on the street, 60 degrees air temp, no burn out before I did some stuff it ran 11.1.... when I did that it had stickier tires, more suspension, lighter wheels, and some motor stuff.
Id rather smoke the tires and run faster on a smaller tire..... thats just me.
It all depends on the car and whats done to it.
I know two guys in the 13's that ran slower on a 15X10. Im sure there are a lot more.
Like I said, look at the 8.5 class and see how fast they are. Run as small a tire as you can still being safe and the faster you will go.
Then again I don't build my car or race on a budget, can't go fast on a budget and have everything hold together......
Id rather smoke the tires and run faster on a smaller tire..... thats just me.
It all depends on the car and whats done to it.
I know two guys in the 13's that ran slower on a 15X10. Im sure there are a lot more.
Like I said, look at the 8.5 class and see how fast they are. Run as small a tire as you can still being safe and the faster you will go.
Then again I don't build my car or race on a budget, can't go fast on a budget and have everything hold together......
