How wide an 18" tire can I run on the back of a first gen?

[q2quest]

I understand in a 17" tire a 275 is about it. In an 18" tire someone suggested a 285 might fit. Can anyone tell me. I'd like to not have to minitub. Thanks-Paul

[Mkelcy]

I understand in a 17" tire a 275 is about it. In an 18" tire someone suggested a 285 might fit. Can anyone tell me. I'd like to not have to minitub. Thanks-Paul

I've got 275-35 18's on the back of a 1968 Camaro. 285's might be possible if you had the back spacing perfect; but they would be very tight. The issue is when one side of the rear end is dropped while the other side is forced up into the wheel well, as when going into a driveway at an angle.

[CAMAROBOY69]

285/40-18 would be tight but it is possible. I run 275/40-18 on the road and on the track. I rolled my rear lips for extra clearance.

[scogin918]

I'm running a 275/40/18 on a 10" rim on the back and I had to make some room. The tire was smashed up against the inner fenderwell. I have just enough room by the outer lip of the fender so I couldn't use a spacer (spacers=bad). I used the 10" rim to staighten up the sidewall. It did but it wasn't enough. I ended up cutting about a 1/2" - 3/4" of metal out of the trunk/floor pan along the side of the inner fenderwell and brought the fenderwell over and welded it to cover the gap. Plenty of room now. As you can see in my sig, I don't have to worry about the stock shock towers though.

[CAMAROBOY69]

I am about to find out about rear shock clearance. I am going to be ordering QA1 shocks for the rear this week. The front suspension of my car is absolutely perfect the way it is IMO. The rear needs some adjustable shocks to dial in the cornering a little more. Still corners like its on rails but adjustable shockes will help even more.

[Ralph LoGrasso]

285/40-18 would be tight but it is possible. I run 275/40-18 on the road and on the track. I rolled my rear lips for extra clearance.

285/40/18 is a 27" tall tire. You'd probably fit a 285/35/18 before the 285/40. Are you sure you're running 275/40s and not 275/35? The extra sidewall is great for traction, and looks good, but it makes clearancing tougher.

[CAMAROBOY69]

285/40/18 is a 27" tall tire. You'd probably fit a 285/35/18 before the 285/40. Are you sure you're running 275/40s and not 275/35? The extra sidewall is great for traction, and looks good, but it makes clearancing tougher.

Yes I am running:
Nitto 555R extreme 275/40-18 rear.
Nitto 555R extreme 235/40-18 front.
I bought the wheels directly from Steve Rupp's blue 69 Camaro. He was running 285/40-18 with tire rubbing issues. He said go with 275/40-18 so I did. So far I have no problems. I rolled the rear quarter lips and that gave me extra clearance. You can even watch my videos from Gingerman raceway. You wont hear any tire rubbing on any of the corners.
However I am running a 9.5" wide wheel on the rear.
You can also go to http://www.adfabdesign.com/Illusion/...Wheels.htmland see the tires and wheels there.

[Ralph LoGrasso]

Yes I am running:
Nitto 555R extreme 275/40-18 rear.
Nitto 555R extreme 235/40-18 front.
I bought the wheels directly from Steve Rupp's blue 69 Camaro. He was running 285/40-18 with tire rubbing issues. He said go with 275/40-18 so I did. So far I have no problems. I rolled the rear quarter lips and that gave me extra clearance. You can even watch my videos from Gingerman raceway. You wont hear any tire rubbing on any of the corners.
However I am running a 9.5" wide wheel on the rear.
You can also go to http://www.adfabdesign.com/Illusion/...Wheels.htmland see the tires and wheels there.

Adam no worries at all, I just thought it might have been a typo. A 275/40 is 26.6" tall or so, so it'd probably present slightly less rubbing issues as opposed to the 27" tall 285/40. Nittos are also notorious for running a bit small with regards to other brands. Your tires fit fine though, so no worries there.

[CAMAROBOY69]

Ralph the most important point to remember is that as you go from a 275 to a 285 you not only go taller you go wider. Most people have a hard time grasping that. For the camaros I see no problem at all going taller. Its the width that kills us. I could not go any wider at all without problems. However I have no problem at all with the height (diameter) of the rear tires on my car.

285/40-18= approx--26.98dia--11.22width
275/40-18= appros--26.66dia--10.83width

I actually posted a pic a long time ago of my wheel and tire tucked wayyyyy up into the wheel well with no problems. It was in my lowering thread. Obviously I didnt run my car THAT low but the tire had the potential of going up into the wheel well.

[Ralph LoGrasso]

I agree, the width is the most significant thing, but as you increase width and maintain the same aspect ratio, height also increases, that's what I was referring to. I understand what you're saying though, and as I said before, Nittos tend to run small (the 315 555DR is a great example of this). If you were to measure a 285 Nitto, I'd bet it'd be closer to 10.5-10.75" wide as opposed to the 11.22".

[4MuscleMachines]

Here are a few pics of a first gen with a 295/35/18 tire on a 10" wheel, NO mini-tubbing. It's a 69, so it has a bit more spacing for it. I included a pic of the car so that you can see how the size looks on it.

The wheel well lip was trimmed and/or rolled and the wheel well molding was trimmed. The molding was trimmed after the tire showed some very slight rubbing against it. After the trimming, no rubbing whatsoever, e.g. up driveways, over speed bumps, ect.

[ProStreet R/T]

335/30/18 :D Takes a little pursuasion but it can be done.

285 should fit no problem with properly sized/spaced wheels.

[CAMAROBOY69]

Here are a few pics of a first gen with a 295/35/18 tire on a 10" wheel, NO mini-tubbing. It's a 69, so it has a bit more spacing for it. I included a pic of the car so that you can see how the size looks on it.

The wheel well lip was trimmed and/or rolled and the wheel well molding was trimmed. The molding was trimmed after the tire showed some very slight rubbing against it. After the trimming, no rubbing whatsoever, e.g. up driveways, over speed bumps, ect.

Tom Izzo's 69 Camaro. What a beauty!!! Well Tom used to own it. That tire has to sooo tight in there.

[Steve Chryssos]

The 275 tire assumes no mods and "off-the-rack" wheels. Anything wider and you are looking at mods and or higher priced custom spec wheels.

So, first thing to determine is your tolerance for mods and expenditure.