BSheppard

I have a C6 that I would like to get 325's under the rear. I don't really want to do the wide body but do want the wider tires. After searching I have found a thread that said a 19X11 rim with 79mm offset will hold a 325 30 19 tire under factory fenders. Is this true? I like the looks of my factory rims. Does anyone have a remake of the factory rims but in the 19X11 with the 79mm of offset? I was thinking that if they do, I could just buy the rear rims and then but 265 35 18s on the front. Any problems with this idea?

I would go with 305 30 19s but there are so few runflat options in that size. Is there even a runfalt in that size?

oldmansan

You could widen a set of stock wheels (front and/or rear). I also like the look of the stock 5-spoke C6 wheels, but they don't accomodate large tires.

San

timd38

Call CCW they can make you what you want. They will not look like the OE wheels, but they have a great selection of wheels.

SpinMonster

79mm would stick out from the fender. If ou go from a 79mm 10" wide and want the same distance to the fender as the stock 10" the offset would be 92mm. A 88-92mm would fit under the stock fender.

Many people misunderstand what offset and backspacing are. Offset is the distance from the midpoint of the wheel width to the inside edge of the wheel's hub so if you go wider that 10" you add 1/2 the new width to the offset or about 12.5mm to have the same distance to the outside edge of the rim. If you make a wheel wider but keep the same offset it moves the wheel outside the fender.

To illustrate, the front wheel on the back of the car isnt 79mm but it looks to be about the same (actually 4mm closer to the fender) with a 54-56mm offset. Why? Its only 8.5" wide.

A 11" wide 79mm offset is adding 13mm to both sides of the hub and would stick out of the fender by about 8mm.

A 305/30/19 would be shorter than the stock tire and would activate active handling quickly as it wears since the car expects a 26.9" tall tire. A 325 runflat would work on a widened rear wheel to 11" but it will bulge a bit. Its been done before but I dont see much of an advantage in traction sibce cars running Z06 fenders dont gain much in traction with that tire let alone a car running it on a rim that is less than 12" wide. An 11.5" rim would work; it will touch the control arm when jacked up but not in actual use.

dennis50nj

http://www.1010tires.com/WheelOffsetCalculator.asp

C6 CYAA

19 X 11 w/ 79MM offset... perfect fit. No rubbing anywhere.

BSheppard

Thanks for all the help guys. Looks like it's 4 new wheels, wide body or just going back with 285's. I thought I would get more traction out of the 325's on 11" rim. I have some time in a Z06 and thought it had a little more girp than my car. Not sure at this point if it is not better just to stick with stock and not mess with the active handling.

BSheppard

Those look great! Who makes them? Does your active handling act up on you?

C6 CYAA

I Forged / Swift. Everything works great! I've been running them for a year.

C6 CYAA

I agree with Spin that a 325 on an 11" rim would not give you the same performance as on a 12" wheel. A 12" wheel will not fit under the stock C6 fenders. The best of both worlds may be a 305 or 315 on a 11" rim. The tire would perform closer to it's maximum potential. A 325 on a 11" wheel would not perform near it's maximum potential. It would be interesting to see the actual tread patch widths of a 305 and 325 on a 11" wheel.

dbratten

Another option you have is to take 18x8.5" front rims and widen them to 11" which will result in an 88mm offset. This will run around $200/wheel. I'll leave it to you to see if tires are available for your needs.

I'm taking a pair of 17x9.5s out to 11.5" for use on the rear with base brakes.

--Dan

Wayne O

My current street wheels/tires are CCW SP16A wheels, 9.5” x 18” front / 11” x 19” rear with the Goodyear Eagle F1 Supercar EMT’s...275/35ZR18 front / 325/30ZR19 rear (Z06 tires). The fronts have a backspacing at 7.75" which is 64mm offset. The rears have 9.15" backspacing which is 79-80mm offset.

I don't do many high RPM 'drag strip' launches off-the-line. Despite the ease with which I can break my tires loose, I feel going to the larger size wheels and tires did make for an overall improvement in traction and handling. The supercar tires are better (in this regard) to the OEM C6 tires and I felt the additional size helped. IMO the larger size tires seem to soak-up small bumps better and the car simply 'tracks' better through curves. Before I went to dedicated track tires I used the Z06 tires on road courses as well. There's no question in my mind...the larger Z06 supercar tires were an improvement over the OEM size C6 tires.

I plan to tub my wheel wells to go with 12" rear rims for track (road course) use but I feel the Z06 tires on 11" wheels is a worthwhile upgrade for street use. My Z06 rear tires protrude slightly from the body but it's pretty neglibible IMO.

BSheppard

Those also look great. I'm back to thinking maybe the 325's are the way to go. Any of you have active handling problems with the wider front and rear tires?

BSheppard

I would want the 19's on the back to be widened. I love the look of the factory rims so much I might would go this route. Who will do this work? Any one have a source? How does that work with the offset?

C6 CYAA

I was hoping Wayne O would comment on this thread. His car was the first I saw with 325's. I will be moving up from my 305's as soon I burn them up.

dbratten

I only mentioned widening the 18" front factory rims as an alternative that may give you additional tire options in that size.

You can add 1" to the factory 19x10s and have a 92mm offset and 9.62" backspacing vs. the OEM 79mm offset and 8.62" backspacing. When widened all the addition goes to the back of the wheel.

I'm using Weldcraft Wheels to alter mine.

--Dan

SpinMonster

Your wheels are not a goiong to fit a 325 which the OP is asking about.....they will touch. I would check on the info you have.

I think you were misinformed.

Your wheel fit great but what size tire is that? This thread was originated specifically about using the 325 Z06 runflat and my comments are specifically about that tire. The burgundy car below has your offsets and the 325 clearly bulges too far out and will touch if it is lowered like many cars are.

On a side note, your car looks awesome and the gunmetal with the silver was a first rate choice. Its unique and doestn look like the chromey rice jobs some people try to have. I only like chrome on red or burgundy cars. Comp gray on my white car would look good as your wheels also would.

This is what I did. The 19" with 11.5" added will touch the control arm if jacked but not in driving use. The 325 runflat will fit this way as it also will with a 11" wheel but as you can see in the pictures below, they are a little bulged. On the 11.5" wheel, they look a bit less bulged.

In the below example a 79mm offset such a wheel would have to add 13mm to the front lip distance making them 79mm but then they would be 13mm closer to the fender and a bulging 325 tire will absolutely touch as he already says they do touch. The ACE slick wheel I had that was such a wheel with a 79mm offset and could only fit a 295 without touching the fender. A ruler would be a good idea with your back wheels as the judge. Just look to see where the wheel would be if moved out 13mm to see for yourself and then see where a bulging 325 would be touching.

The bottom pciture shows the tire clearly outside the fender's path. On my car which is pretty lowered, it will crack the fender. My 79mm 19x11 ace slick wheels with KDW2 295's touched in the front of the well although they looked to not touch as the silver car above which I'm guessing has a 305 whcih isnt as tall as a KDW2 295 at 27" tall.

knkali

I have a set of OEM 19's going here this week to get widened 1 inch

http://www.ericvaughnmachine.com/About_Us.html

Gotcha

Heres a thread when I widened my stock rears 1" to a 19x11

I wanted the outside face of the wheel at stock location so I cut the fender liner for clearance. It could also be done, without cutting the liner, by using some thin spacers and ET lug nuts.

http://forums.corvetteforum.com/c6-c...es-w-pics.html

Gotcha

There's more work involved to run a 19 x 11.5" widened wheel, I just helped a local guy do it a few weeks ago.

An 11" widened wheel will touch the control arm when the car is jacked up (or the suspension in unloaded). If you add 1/2" more (11.5"), the wheel will hit the control arm before it mounts up against the hub/rotor. Even if you used the lugs to force the wheel on, which would be binding/bending the wheel, the wheel would hit the control arm if the suspension unloaded in use.

I highly recommend control arm clearance. I might be an exception but I get my car airborn sometimes. There's some hills near me, when crested at 50-60 mph, that will get my rears off the ground, even setting off traction control. So at 60 mph were looking at a wheel speed of around 760 rpm, not a good time for the wheel to hit the control arm.

Anyway, for the 11.5" wheel we used a spacer (1/4" with ET lugs) and LPE shock mounts to raise the negative suspension travel to give control arm clearance.