What size rim and backspacing for 275/50/15 tires?

[Cable]

Hey guys, as some of you know I have completed my 383/TH350 swap and found that my 195/60/14 will be dead soon (duh!).

 

I think I am going to attempt to stuff 275/50/15's under rear of my 280z.

 

I have searched the forums and haven't found anyone that has run this size tire in a stock wheel opening.

 

I found a company (http://www.wheelvintiques.com) that will custom make me a steel rim in any size and backspacing I want. The question is, what do I need?

 

I have stock, non-flared wheel openings. Although I am rolling the edge of the inter fenders this week and have the coilover conversion stuff on order. The lower spring perch will be above the tires, so I'll gain max tire clearence.

 

Do you think a 15x8 w/5.0 of BS will work with this large tire? If not, what would?

 

Thanks guys!!

[Tim240z]

5" back space will work if you have coilovers. That wide of a tire will need a 10" wide rim to properly fit and thus you WILL need flares.

There are some wide 16" rims posted in the classifieds.

 

Tim

[Dan Juday]

I'm running 265/50/15's on the front on 8" rims. I think with a 275 you could run 9" wide rims with no problem. But I still don't know if you could fit that in the rear wheelwell. I have 4 1/2" of backspacing but I have 10" coilovers and tall tires in the rear. I wanted to signifcantly lower the car so it was either that or use some rediculously short spring and sacrifice ride quality.

[deMideon]

It really depends pm the tire manufacturer etc. Take a look at Tire Rack:

http://www.tirerack.com/

They have a specs listing for almost all of the tires that shows rim width range. It is different for different tire, brands, and models. So take a look!

[Cable]

BFG says that the rim needs to be between 7.5" and 11" wide for the 275/50/15 tires.

 

 

I am not willing to run fender flares.

 

 

I figured this would work since there are those saying they are using 26x10.5x15 slicks on a 15x8 rim.

[JMortensen]

BFG says that the rim needs to be between 7.5" and 11" wide for the 275/50/15 tires.

 

Yeah, it will FIT on the rim. Sure. But it won't WORK very well on an 8" rim.

 

Take it from a guy who is running a 250/45/15 slick on an 8" rim and wishing he had 9" or 9.5" rims. Then again, if you like that balloon tire look and don't really care about the handling, then it will fit...

 

EDIT--Drag slicks are MUCH different than low pro street tires. The sidewall of that low pro is going to be stiff, which is where the problem comes in.

[Cable]

I see your point.

 

I am willing to get whatever width rims is necessary, as long as I don't have to use fender flares.

[JMortensen]

With coilovers done right and rolled fenders I think a 9" rim will fit. I haven't tried myself, but with my 8's and the amount of space, that's my best estimate. That puts you somewhere in the 245 to 265 low pro tire. I would use closer to the 245 myself, but I'm more concerned with handling than going fast in a straight line.

[Cable]

You are right, I am more concerned about going straight vs turning.

[74_5.0L_Z]

I have two sets of wheels for my car.

 

Set 1: 15 x 8 with a 5 inch backspace have 245/50/15 Dunlop SP8000 tires. The tire clears my rear coilovers by <1/4" and is even with the fender lip.

 

Set 2: 16 x 8 with 5 in backspace has 245/45/16 Hoosier A3S04. Again my tire clears the coilovers by 1/4" and is even with the stock fender lip.

 

My coil-overs are Ground Control units with 250#/in 10 inch x 2.50 springs. It would be possible to run more backspace and a wider tire if you ran a shorter spring (8"). The shorter springs will let you raise the perch location above the tire and get more clearance. The additional clearance could let you squeeze a 15 x 9 with a 5.75" backspace and a 275 if you also roll the rear fender lip. That is the only way you will get the 275/50/15's under the stock fender. Unfortunately, you would have to run a stiffer spring (300#/in +) to keep from stacking the short springs, and stiff springs are not ideal for drag racing.

[Clifton]

Why a 15"? A 275-50-17 will look like a truck tire. There is hardley anything available in that size. A 275-40-17 will actually be shorter and give you more room on the strut side. An 18" would be even better and 35 series tires are available keeping the same over all diameter. I did get a 275 to fit but I don't know if you can do a 15 with out rubbing.

 

Here's what I did http://www.geocities.com/clifton_ragland/Tires.html

[74_5.0L_Z]

I believe that he wants a 15" wheel so that he can run a tire with some sidewall. Tires with a taller sidewall are better for drag racing. The BFG DR are available as 235/60/15 and 275/50/15.

 

I do agree that it is easier to get the clearance with a larger diameter wheel. My 16" wheels/tires have slightly more clearance than my 15".

[z-ya]

I'm running 245-45ZR16s on 16x8" rims with a 5" BS. They fit, and come real close to the coil-overs. I had to roll the rear fender lips to prevent rubbing. If you are running the stock ride height, you won't need to roll the fenders. For 275 width tire you certainly will need 9 or 10" wheels, and flares.

 

Pete

[Cable]

I believe that he wants a 15" wheel so that he can run a tire with some sidewall. Tires with a taller sidewall are better for drag racing. The BFG DR are available as 235/60/15 and 275/50/15.

 

I do agree that it is easier to get the clearance with a larger diameter wheel. My 16" wheels/tires have slightly more clearance than my 15".

 

 

You are correct. I want the 15's because its prefered for drag racing.

 

For now, I think I am just going to stick to 235/60/15's, but down the road, who knows.

[Guest nbko5v5]

I seem people w/ stock suspension and no flares running 285/35/18 in the rear .... it is possible if you have the money ...

[Cable]

I seem people w/ stock suspension and no flares running 285/35/18 in the rear .... it is possible if you have the money ...

 

 

Umm, how?

[Brad-ManQ45]

I think my 7th edition of the JTR manual says that you can raise the spring perch on the rear 2", and use 280ZX 2+2 springs with 3 1/4 coils or so cut out, and be able to run a 245/50/16 tire on an 8" wheel w/5.5" backspacing w/no modifications to the wheelwells.

 

I believe they said that the spring rate would be around 200 lb/in.

 

I don't think that's too far off the Tociko spring rates....

 

The nice thing about this would be that you could run a 26" tire

 

You could get a nice drag slick on an 8" rim in a 14" size with a high sidewall that would be great for drags under there. Or lose a little sidewall and go with a 15" heel AND 8" rim.

 

If you're looking at DOT leagal tires, then stick with a 15" rim and drag radials.

 

You haven't said what your use for the car will be, which we need to know in order to help you better.

 

If you are going to autox or roadrace, we need to know that.

 

By the way, for autox, you really don't want a 17" or larger wheel. Smaller whee/tire combos tend to be more predictable on the ragged edge.

 

That, and they weigh less too! (Same for drag wheel/tire combos).

 

Remember, you get a 1.5X hit because you're talking about rotational weight here. It takes less horsepower to accelerate the smaller in diameter wheels with the same overall wheel/tire diameter (the proviso being that you arte comparing the same wheels in different sizes - same rim width). The taller wheel HAS to weigh more.