my current setup

18x9 rpm r-505 painted black 24lbs each
275/40 rear
245/40 front

looking at getting
17x9 5 Zigen black fn01rc's 17 lbs each
I was told that I could get all they way to a 315 tire on the back.

This z is now going to be used for weekend cruizing/drag/autocross. I am not worried about the style of the rim as much as the performance for both drag and autocross.

what do you guys recommend for tire sizes?

 

I have already posted this in the rim/tire section

 

the guy at the shop I am working with is suggesting a 315 tire in the rear

 

I wouldn't put a 315 on a 9.5" Rim. I would just run a square 275 set up with a quality tire like the RE-11. It is a bit stiff for drag, but it will offer great performance in autox and solid traction on the strip.

 

315 on a 9-9.5" no way Id do that

What offset?

 

315?! I think that's overkill. I would stick with 275 unless u got FI.

 

ok. looks like the rear is 17x10

 

Do you want more of a drag tire than can autox or an autox tire that can drag? Your best bet if you are going to do either activity often is to run you DD wheels with autox tires and get a cheapo set of rear wheels for dragging.

Regardless, 315 is too big on a 9.5, and is hard to fit no matter what wheel width you have. You don't need huge tires for drag racing, even sticky 255s suffice for 600rwhp cars running low 10s.

 

I still wouldn't run that big of a tire on a 10". Do you plan to go FI?

 

no i don't what about 295 for for 17x10 rear?

 

not looking to go F/I. I understand that 315 is overkill. I was just wondering

 

I would just get 9.5's and run a square 275 set-up. You don't need that big of a tire for either drag or autox. Just get a quality tire and you will be fine. I get "adequate" traction for drag with my 255 azenis.

 

by getting these new rims i will be saving about 7 lbs per wheels. About how much of an improvement could i expect to see in the 1/4? .1,.2?

 

The improvement depends on what you run now.

If you run low 14's @ 98mph (slower than stock) with mods, then with DR's you will do slightly better.

Driver mod > DR's

Good driver NA with DR's in a DE is mid 13's EASY. I wouldnt go more than a 275DR on an NA car, any more is slowing you down.

 

im going to go with 275, just trying to see if it is worth the $900 for the rims alone

 

where would you suggest getting a set up cheap light weight rims for drag?

 

Summit has some weld knock offs for $124 a piece in 15x8 for drag purposes. I am going to get a set and match them with 255/60 MT drag radials. As stated above 275 DR's would likely be overkill for your set-up. I would get some more seat time on streets first though.

 

Old rx7 FD rims are 13.8 or 16lbs and work with our cars. You can ebay a rear set for cheap and put DR's on

 

Also a good option.

 

thats not a bad idea at all