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View Full Version : 275/40/17's on all four corners now complete.



CarlC
10-15-2004, 06:45 PM
There's several here that have asked questions about fitting 275/40/17's on all four corners of my '68. There's now a new section on my website with pictures and text that shows the swap. Hopefully it explains most of the changes needed to make the fitment work.

If there's any questions please fire away.

68protouring454
10-15-2004, 08:13 PM
carl, that is awesome, tried getting to site but typical geocities all clogged up, can't wait to see what you did, i would love to run 275's on front of my 68, goodwork, i got site to work but only the top pic works the rest have red x's on them, any reason why?? thanks
jake

toofun
10-16-2004, 02:59 AM
I never would have thought it possible. Are there any other mods or problems you should worry about? Am I right to assume this would work on a 69 as well?

TOOFUN :rolleyes5

toofun
10-16-2004, 03:41 AM
I was lucky enough to get on your site but had a couple of more questions regarding this package. First you said to use the speedtech arms. Are these the same as the global west arms? Also you never mentioned the backspacing needed for the front rims. Also did you run into any problems with the fender wells? Everyone in the world always told me that the biggest tire you could fit on these cars was a 245 with 17x8 rims with 5 inch backspacing. I believe you did what you did, but just wondering what the down side is to this package may be and how no one has been able to do it before. My hats off to you.

TOOFUN :seizure:

spanky the wondermuffin
10-16-2004, 05:57 AM
i have said for a couple years now that a 275 will fit up front.i guess your 68 and my 68 must be real oddballs.or a 275 DOES fit after all.i sure hope everyone who argued with me will now jump back in and tell carl he is wrong also.

CarlC
10-16-2004, 09:09 AM
The backspacing front and rear is the same. I wanted to be able to rotate tires since the road coarse eats them up fast. The rims are 17x9.5x5.5bs Vintage Wheel Works V45 with Nitto NT555RII autocross/track day tires.

I don't know if the GW arms are the same but it figures that they would be similar. Lower A-arm clearance starts to get tight as well but the upper is the primary problem. Having the steering limiters makes the job much easier.

Mechanically it should fit a '69, but I don't know about sheetmetal clearances. The front tire diameter and overall width is the same as a 245/50/16, and those fit, so it may work. Test fitment is the only way to know for sure.

Drawbacks? Yes, the steering is limited, but the car can do a 3-point turn on a narrow street so that's good enough for me. If the car has to have the full stock steering sweep then a narrower rim is in order. I just allow a bit more room for slow speed maneuvers.

Here's the text and pics from the website since it's geocities bandwidth limited.
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With a stock subframe? Yes. With stock A-arms? No. In the following section the installation of Speedtech A-arms is covered, and they are the key to fitting big rubber on the front of the car. The arms allow for more clearance of the rim and have a built-in steering limiter that makes adjustments easy. Some steering needs to be dialed out and the suspension rebound travel must also be limited to around 2.5" from ride height. This is with -1.8* camber. With less negative camber the clearances will be better (upper arm is the limiting factor) and will allow for more steering and rebound travel. The car needs to be on a track to determine the best track-only camber setting, but for the street a -1/2 to -1* setting should work fine. Steering is fine around town with the limited turning radius if care is taken to allow for a bit more turning room than normal. The rears require rolling the fenderlip from the 10-2 o'clock position if you have the stock full-width fenderlip. The fenderlip on this car is very wide and can be rolled fairly easily. The difference in cornering power is like night and day. Braking is much improved as well. The ride with the RII autocross tire is harsher than the more ballon-like BFG Comp T/A ZR 245/50/16's that were on the car, but it's well worth the tradeoff. The 275/40/17 size is the same as the C4 'Vette so availabity and compound choices are very good Due to the increased backspace of this rim it was necessary to slightly re-clock the flexible brake lines at the caliper for rim clearance.

The overall width difference of a 255/50/16 on an 8" rim vs. a 275/40/17 on a 9.5" rim is only 1/4" (275 is wider). However, the 275/40 lays down nearly 1.5" of additional tread width to the road. That's huge.

https://static1.pt-content.com/images/noimg.gif
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Rick Dorion
10-16-2004, 09:20 AM
Carl - thanks! My budget hates you!

Spanky - never doubted you!

With a hydroboost going in I've been wanting to do something like this for maximum braking effect as well.

There will be 16x8" V45's for sale this winter with low mileage tires!!

CarlC
10-16-2004, 09:27 AM
Carl - thanks! My budget hates you!

Ha! I'm building a second bathroom for the house, that's the tradeoff with my wife for the Camaro. I like building fuel lines a lot more than sewer pipes.

Talk to Rusty at VWW. As a returning customer he should give you a break.

OHCbird
10-16-2004, 09:40 AM
CarlC-

I keep getting the Geocities transfer rate thing... Why don't you shoot me the HTML or whatever you have it in, and I'll host it on my site... I've got tons of bandwidth left (for now).
JEFF

Ralph LoGrasso
10-16-2004, 02:19 PM
Carl,

Awesome! I've been planning 265/35/18s for a long time now, but I was also going to attempt some 275/35/18s as well.

edit: Carl you have a PM.

rocketrod
10-16-2004, 07:00 PM
The 69 Camaro I sold last month had 17x9.5 TT IIs with 275/40/17 in the rear and they rubbed the inner wheelwells (the fenderwell lip was rolled which still left very little clearance). Now granted I had the stock leaf springs, cheap shocks and tires, but I was not taking corners hard at all and they rubbed. Can performance leaf springs, shocks and tires correct this??? Any feedback would be appreciated as I really would like to put 17x9.5s on all four corners, after doing the ST upgrades of course.


Rod

CarlC
10-17-2004, 12:08 PM
Did the return PM come through?

Ralph LoGrasso
10-17-2004, 05:25 PM
Yup, I got it. Response coming.

MarkM66
10-18-2004, 06:47 AM
Carl, do you know if you have the short steering arms? I tried mounting that same size wheel/backspacing on the front of mine, and it hit.

Mine also hit the rear of the inner fender way before full lock. Mine also sat probably 2" lower then yours, so that's probably what caused that issue.

MarkM66
10-18-2004, 06:51 AM
i have said for a couple years now that a 275 will fit up front.i guess your 68 and my 68 must be real oddballs.or a 275 DOES fit after all.i sure hope everyone who argued with me will now jump back in and tell carl he is wrong also.

Well there certainly are other variables to consider. Tried it on my car, and it didn't work. For reasons stated above.

CarlC
10-18-2004, 04:30 PM
Mark,

Short arms and no clearance issues.

I'll have to crawl underneath when I get home and see if a longer arm would be a problem.

nkopper
10-22-2004, 12:19 PM
Maybe Charlie Lillard will have to answer this, but did Mark Stielow modify the inner fenders on the Red Witch to fit 9.5" rims and 275 tires? I keep looking at these pics (link below) to figure out how the tires fit on a car that low with the factory subframe and factory notched a-arms. Did the 'vette spindles make the difference?

http://www.hotrod.com/featuredvehicles/45038/


Nathan

baz67
10-22-2004, 09:16 PM
The Red Witch has 255's on the front. I just was at his place and checked it out. To answer your question though, yes the inners are modified. The inner is about a half inner. It does not connect to the fender.
Brian

CarlC
10-23-2004, 07:49 AM
Carl, do you know if you have the short steering arms? I tried mounting that same size wheel/backspacing on the front of mine, and it hit.

Mine also hit the rear of the inner fender way before full lock. Mine also sat probably 2" lower then yours, so that's probably what caused that issue.

Mark,

Longer steering arms will be a problem. You might be able to get away with 5 5-1/4" BS but it would be close. Short arms are the way to go. I'll update the info on my website. Thanks for calling that out.

With 6* caster and the center of the sphere of he lower ball joint 1/4" lower than the lower front A-arm pivot bolt at ride height there are no clearance issues. It's really close on the passenger side, but has 3/8" clearance on the drivers. Sheetmetal differences from car-to-car will have to be accounted for. Running a bit less caster will free up some room.

The Red Witch, what a great car. If I was ever to build another....
But, I don't believe that ride height can be combined with a stock spindle and keep a favorable steering geometry. The Witch, by using my calibrated eyeball, is 1.5-2" lower than mine. If I lower mine any more the under-braking bump steer gets scarry. If the Corvette spindle has more drop than the stock spindle then a better geometry can be obtained.

68protouring454
10-23-2004, 08:55 AM
great info carl, i am going to go for 275's up front as well, with 335s in the rear it should help, do you or anyone else know if the vette spindle neds modifying to work on the first gen?? i am interested in it, what would you use for a steering arm on the vette spindle, i have to dig up the witch article
jake

CarlC
10-23-2004, 10:36 AM
I don't know what mods are necessary to fit the spindle, but maybe David Pozzi has some info.

Tyler is working on a spindle that may be similar to the Corvette.

Jeff, thanks for the website offer. For a few days after something new is added the allocation gets used up. After that its OK. Anybody know a simple html editor for dummies?

MarkM66
10-26-2004, 08:17 AM
Thanks for the update Carl.

I did run 5 1/4" backspacing on an 8" wheel, and it was VERY close.