I have read threads until my mind is about to explode trying to figure out tire fitment for my 89 IROC. Car will be lowerd on Hotchkiss springs. Want to have good tuck and little or no rub under normal driving/parking circumstances. Can roll front and rear lips and don't mind some light hammer work to clearance. Would prefer not to run spacers. From what I have looked at, it looks like 19x10 rears with 295/35/19 and 5.5 backspacing should give me what I want in the back. On the the fronts, I'm looking at 19x8 with 245/35/19 and 4.5 backspacing. Probably most unsure if I am doing the right backspacing. Likely doing a Boyds wheel, so I have some flexibility with Back Spacing. Has anyone got any pics with this tire/wheel size combo? I have looked but haven't seen much with 19. thanks!!

Should also note that car has factory rear disc brakes and I am upgrading to LS1 brakes for the front.

 

5.5 backspacing on a 10" will stick out past the fender lip. I have 18x10 in the rear with 6.5" bs and a 305/35/18 tire. Had to do some mods to the inner fender well around the bumpstop. Fronts are 18x9 with 5.5" bs on 275/35/18....no mods in front at all.

 

6-6.5" would tuck them in. My 19x10's are c6 vette take offs and are 8.11" or so backspaced i believe 79mm offset so it should be 8.11". I have 4th gen spec rear which is almost 2" wider, probably 1.875" wider per side and i have a .625" spacer on wheel. So thats almost 2.5-2.625" of space added, which should mean 5.5-5.6" backspacing would work for a 3rd gen rear. Mine are just inside fender lip, with 305/35 tire. Heavvvvy inner well work to prevent rub

 

Thanks for the input - what type of heavy inner wheel well work did you have to do? Some time with a 2-3lb sledge or are we talking a lot more? If I went 6.25 on the Baskspace would that minimize the clearance issues while still giving good tuck - clearing rolled fender lips on the outside?

 

Heavy hammering with 2-3 lb sledge and some minor cutting to clear my 27.5" tall drag radials. It only has maybe finger thickness of room still before touching well, but doesnt rub from what i can tell. Tire is just under outer lip tho. Didnt roll lip but looks like it will clear if it ever squatted down that low

 

I have 19s all the way around, but my bs and mounting pad were altered to accept the Brembo brakes off the new SS. I have a nice tuck, with no rub at any corner. An adjustable panhard bar makes life a lil easier also.

 

Copchaser - Do you know what your rim sizes, backspacing, and tire sizes are? I have seen you car and like the combo you are using. What type of mounting pad mods did you do? I already have an adjustable panhard bar to install with the rest of the suspension mods next month.

 

It's been a while, but I believe the front bs was 5.75 and the rear was 6.0. Mounting pad is .5inch on all four. 19x8 255/35s.. 19x10 295/30s

 

The sheet metal is 2 or three layers thick..(can't remember) in the bumpstop area. I cut it out and welded in a patch panel. I've got and extra 2-2.5". No fender rolling was required. 6.25" bs and a rolled fender should be fine....with some inner hammering or cutting but definitely the best look in my opinion. Either way if you go less I don't think you'll be happy with the look. (Based on what I've gathered from this brief post)