The Backspacing Blues - Team Camaro Tech
Wheels & Tires What fits what?

Reply
 
LinkBack Thread Tools Display Modes
post #1 of 23 (permalink) Old Mar 2nd, 01, 09:57 AM Thread Starter
Tech Team
 
Join Date: Jul 2000
Location: Beatrice, Nebraska
Posts: 74
Unhappy

Well heres the dillema. I want to run TT II 17x8 and 17x9.5 on my 69. I would be running a 245/45 on front and 275/40 on the rear. From what I gather A 4.5 bs on front will work well but is custom, and a 5.5 bs on back will work. Even though I will be using Hotchkis comp springs and moving My shocks inboard of the frame rails. I have gone through all the posts on this subject and everyone says it will work but is any body running these that can verify they'll work??
golopogos is offline  
Sponsored Links
Advertisement
 
post #2 of 23 (permalink) Old Mar 2nd, 01, 07:12 PM
Senior Tech
 
Join Date: Feb 2001
Location: Riverside, Ca. 92508
Posts: 137
Post

I have a 245/40/18 on TT II with a 4 1/2 backspacing for the front of my 69 and they are fine. I know of a couple of people that have 275/40/17 on the rear with 5 1/2 backspacing and as far as i know they fit fine. Good Luck!!
jenndon is offline  
post #3 of 23 (permalink) Old Mar 3rd, 01, 03:41 AM
Senior Tech
 
Join Date: Dec 1999
Posts: 1,515
Post

The front will be fine. I've heard of people running 275 on a 9.5 with 5.5 bs, but to be on the safe side I'd do some measuring on your car. Rear ends are usually shifted a little, so measure both sides. Tire specs can be found on the manufactures web site, you'll need to know section width. Add it all up for a perfect fit.

------------------
68 468 700R4, and here it is;
mutert23
MarkM is offline  
 
post #4 of 23 (permalink) Old Mar 3rd, 01, 08:50 PM
Senior Tech
 
Join Date: Oct 2000
Location: Long Island, NY
Posts: 269
Post

I have also been considering TT II's for my 69 with the same size tires you mention. From studying the wheels currently on my car and from what I've heard, I will be using 17x8 in front with a 4" bcksp.

As far as the back goes, I don't think 5.5" bcksp will fit in the back of my car unless the inner fenderwell is modified. Moving the shocks really won't help because the fenderwell is the limiting factor. Right now I have 255/60 15 on the car. These tires measure 10.9"(a little wider than the specs listed for most tires of this size) mounted on the rims I have on the car now, Centerline 15x8.5 with 4.875 bcksp. With this setup I have a slight rubbing when one side of the rear end moves up before the other. By my calculations a 275/40/17 tire on a 17x9.5 with 5.5 bckspc will give me slightly LESS clearance than I have now.

Ex>rims I have now have bcksp 57% of rim width (4.875 divided by 8.5 = 57.35%) and a 10.9"tire.

5.5" bckspc on a 17x9.5 rim = 58% (approx) of rim width (5.5 div by 9.5 = 57.89%). And a 275/40 17 tire width is usually listed as 10.9 or 11 inches depending on brand.

I havent done anything to increase the clearance on my 69 yet, so maybe a few good whacks with a sledge would give all the clearance necessary. I'm just a little hesitant to lay out the cash for a tire/wheel combo that will be tighter than the one currently rubbing the paint off both inner fenderwells. I emailed American and am waiting for them to let me know if they offer a 17x9.5 with closer to 5.25 bckspc since they don't show anything less than 5.5 on their website.

Like I said this is all just based on calculations and on the clearance I have currently. If you do go for the 5.5 inch bckspc please post whether you have any clearance problems because I'm looking to get a set of these on my car too...they look awesome!
my69gofast is offline  
post #5 of 23 (permalink) Old Mar 4th, 01, 03:40 AM
Senior Tech
 
Join Date: Dec 1999
Posts: 1,515
Post

Mygofast, I would deffinitally not get a 8" wheel with only 4" of backspacing for the front. I'm running 16x8 with 4" bs, on the rear of my car and tried them on the front and the stuck out to far, it looked bad. A 7" wheel with 4" backspacing would be ok, but if you get a 8" wheel get at least 4.5" backspacing, I'm going to get 4.75".

Here's what I've come up with on the rear: Everyone including myself wants to run a 9.5" wheel and a 275/40 17 tire. A 275 tire has a section width of 10.91", I'll use 11" since it's so close. So if you have a 9.5" wheel that gives you an added 0.75" (3/4") on both sides of the rim. So if you use 5.5" backspacing plus the 0.75 that gives you a total of 6.25". Now measure how much room you have from the wheel mounting surface of your drum or disc brakes, to the inner fender well, and since a 275, is about 26" tall, you should measure this at 13" from the center of the axle. I did these calcuations for Treyman, and his measurement from the wheel mounting surface to the inner fender was 6 3/8" or 6.375". So when you take the 6.375" - 6.25" that only gave him .125" of clearance or about 1/8", that's cutting it a little close so the 5.5" of backspacing may be too much for him. Just measure what you have, and apply the above.

------------------
68 468 700R4, and here it is;
mutert23
MarkM is offline  
post #6 of 23 (permalink) Old Mar 4th, 01, 04:48 AM
 
Join Date: Dec 2000
Location: New York, NY
Posts: 28
Post

Mark M,
Thanks for the information. I am in totla confusion also about backspacing. I have a 67 with 17x7 up front with 4.5 bs and a 255 40 tire (goodyear GSC). There is rubbing on the frame on lock to lock turns-no suspension rubbing or interference. Wheels are tucked in nicely, but I would like to go toan 8 inch up front. How will an 8 inch up front compare to the 7 inch if I go to 4.75 bs on the 8 inch? Will I have at least the same anmount of space that I have now with the 7 inch and 4.5 bs? I realize I may have to go to the 245 b/c everybody says this is as large as I can go.

In the rear I have 9.5 inch rim with 285/40 GSC's. The backspacing is 5.0 (I measured yesterday). Ideally I would love to put 5.5 bs and tuck the wheel in a little more than it is now. Any thoughts. PS Engineering makes a TT knock off for race cars in 17 inches. Not cheap about $400/rim, but they will custom make anything and can have the rims in a few weeks. I am leaning that way b/c I do want teh gray center of a traditional Torq D and AR is not making them yet in 17 inches. I would value your thought on the front and rear bs issues of my car. I can e-maila picture to anybody who wants to see the curent set up for their research.

Thanks,

Brad

<BLOCKQUOTE>quote:</font><HR>Originally posted by MarkM:
Mygofast, I would deffinitally not get a 8" wheel with only 4" of backspacing for the front. I'm running 16x8 with 4" bs, on the rear of my car and tried them on the front and the stuck out to far, it looked bad. A 7" wheel with 4" backspacing would be ok, but if you get a 8" wheel get at least 4.5" backspacing, I'm going to get 4.75".

Here's what I've come up with on the rear: Everyone including myself wants to run a 9.5" wheel and a 275/40 17 tire. A 275 tire has a section width of 10.91", I'll use 11" since it's so close. So if you have a 9.5" wheel that gives you an added 0.75" (3/4") on both sides of the rim. So if you use 5.5" backspacing plus the 0.75 that gives you a total of 6.25". Now measure how much room you have from the wheel mounting surface of your drum or disc brakes, to the inner fender well, and since a 275, is about 26" tall, you should measure this at 13" from the center of the axle. I did these calcuations for Treyman, and his measurement from the wheel mounting surface to the inner fender was 6 3/8" or 6.375". So when you take the 6.375" - 6.25" that only gave him .125" of clearance or about 1/8", that's cutting it a little close so the 5.5" of backspacing may be too much for him. Just measure what you have, and apply the above.

<HR></BLOCKQUOTE>

BradB is offline  
post #7 of 23 (permalink) Old Mar 4th, 01, 04:59 AM
Senior Tech
 
Join Date: Jul 1999
Location: Broomfield, Colorado
Posts: 755
Post

My '69 is lowered about 2" all around and I have 17" TT2's with no rubbing at all. I'm running 17x7s up front with 4" BS and 245/45/17 BFG Comp T/As. An 8" wheel with 4" BS would not fit without hitting on the outside. You could move that extra inch inside (5" BS) and probably be OK.

In the back I have 17x8s with 255/45/17s with 4" BS. However, I have a 9" rear and the width is off just a bit from stock.

I measured my car in the rear and there is 11-3/4" inside space. That's with the lip trimmed back just a touch. Anyway you want to play the BS game, with a 275 tire @ 11" section width, you only have 3/8" each side Max. Even if you center the tire perfectly, I have to believe it wil rub occassionally.

One more thing, if you use lowering blocks in the rear, your lower shock mount drops down so it just clears the 255/45/17 and 17x8 combo. It will have to be moved inward to step up to 275's and 9-1/2" wheels.

------------------
Scott
'69 400SB, Richmond 5-speed
www.geocities.com/sdenning1
RockyMtnRacer is offline  
post #8 of 23 (permalink) Old Mar 4th, 01, 08:39 AM Thread Starter
Tech Team
 
Join Date: Jul 2000
Location: Beatrice, Nebraska
Posts: 74
Post

MARKM you think a 4.75 bs would work better than a 4.5? I hadn't yet looked into going that way maybe I should get the tape out again. I went to the local BFG dealer he can order me the rims with custom BS 4.5 front and ? rear. maybe 5.25?? Heres the thing I think maybe a small spacer with a 5.5 is the way to go, the way I see it is that the tire will be closer to the inner fender than the outer with a 5.5 and maybe a .25 spacer is the way to go to get it perfectly centered without a custom rim????? any thoughts??

------------------
69 camaro 327/Th400
golopogos is offline  
post #9 of 23 (permalink) Old Mar 4th, 01, 09:25 AM
Senior Tech
 
Join Date: Dec 1999
Posts: 1,515
Post

BradB, what kind of wheels are you running now? I'd like to see some pics if you want to send me some. In your front with a 7" wheel and 4.5" backspacing, that wheel should fit in there nice. If you go to an 8" wheel with 4.75" b.s. just imagine the wheel you have on your car now sticking outward aboout 3/4" from where it is now, it should still look good, even if you want to get 4.5" b.s. so you don't get more frame rubbing that should look good too, if the tire/wheel is sticking outward 1" further, will it be to far? You'll have to be the judge of that. As far as the biggest tire/wheel you can go with, well I've seen two 68 camaros is CHP with 9"-9.5" wheels and 275 tires in front, one was a orange 68 with TTII's and it was mini-tubed in the rear and 335's, and the other was a 68 in the Pro-touring shoot-out with vette wheels on it, I don't know how they did it withour rubbing, but who knows they might rub alot. But to be safe I'd stay with a 255 or 245/45. The wheels you have on the rear now seem pretty close to me, but might look better with a little more b.s. If you ever get a chance take a measurement from the wheel mounting surface to the inner fender, this can be done with a couple yard sticks. Have you asked American racing when they are coming out with the cast looking torque thrust? It might be worth the wait. How's life in NY,NY? Many car people in that area?

golo: I can't say for sure if a 4.75" bs will be better than 4.5" bs as far as looks and to avoid rubbing the frame, either way should look and work good. I was thinking about the possible use of spacers too. Since my rear is shifter to the passenger side a little, I have less room on the drivers side as far as clearance from the drum to the inner fender, so I might just have to run a spacer on one side. I'll probably just get the 17x9.5 with 5.5" backspacing and if I get some rubbng, I'll throw just enough spacer in there to end that.

Also have you guys checked out the Boyd Smoothie? They look similar to TTII's but are available in a better variety of sizes, I actually like the looks of them better. go to www.bcoddington.com

------------------
68 468 700R4, and here it is;
mutert23

[This message has been edited by MarkM (edited 03-04-2001).]
MarkM is offline  
post #10 of 23 (permalink) Old Mar 4th, 01, 09:42 AM
Senior Tech
 
Join Date: Dec 1999
Posts: 1,515
Post

Boyd use to have them on there site, they make them but Moon sells them, they are called the "Cast Smoothie" go here if you want to find them http://www.mooneyes.com/01NEW.html

------------------
68 468 700R4, and here it is;
mutert23
MarkM is offline  
post #11 of 23 (permalink) Old Mar 4th, 01, 09:10 PM
Senior Tech
 
Join Date: Feb 2001
Location: Riverside, Ca. 92508
Posts: 137
Post

Go for 18's!!!!
i just posted a pic of our 69 in the exchange...under my toy, check it out and let me know what you think
jenndon is offline  
post #12 of 23 (permalink) Old Mar 4th, 01, 10:26 PM
Senior Tech
 
Join Date: Oct 2000
Location: Long Island, NY
Posts: 269
Post

I actually meant to say 17x7 up front with 4" bck spc...Sorry for the mixup. Thanks for catching that...You guys are sharp!

Golo...I am waiting to hear back from American Racing to see if they will be making the TorqThrust II in 17x9.5 with 5.25 bckspcing but didnt really consider using a spacer. That may be the best solution if the 5.25 bckspc isnt avail.

Does anyone know where a .25" spacer can be purchased?
my69gofast is offline  
post #13 of 23 (permalink) Old Mar 4th, 01, 11:05 PM
Senior Tech
 
Join Date: Oct 2000
Location: Long Island, NY
Posts: 269
Post

MarkM
I like your method of calculating the backspace plus tire bulge. Basically comes up with the same numbers as the way I did it but a little more direct.
One thing everyone should keep in mind when figuring how much space they need is that the space from the tire to the rear inner fenderwell will change as the rear end moves up. This is how it is with my 69. There is enough room when the car is sitting level but when you drive crooked up an incline the rearend shifts and the tire rubs into the fenderwell and sounds horrible.
This is why I know that 5.5 bckspc with an 9.5 will be just too tight with an 11" tire because like I said that leaves a touch less room than what is rubbing now. I could definitely live with 5.25' bckspc and a big hammer for insurance.

Another thing to keep in mind is that the area with the tightest clearance may not be what is closest to the tire when the car is sitting level. When my 69 is sitting level and you look in at the fenderwell, you can see the area with the paint rubbed off is actually about an inch above the top of the tire.
my69gofast is offline  
post #14 of 23 (permalink) Old Mar 5th, 01, 02:14 AM
 
Join Date: Dec 2000
Location: New York, NY
Posts: 28
Post

MARK M

Thanks for the insights. I will measure more when the snow melts. NY, Ny is ok for car people, just need to seek it out unlike California where it seems everybody is a car person.

Check out PS ENGINEERING wheels at their website. They claim to make any offset including 5.25 or anything we would want per application. Not cheap, but what is another $ 400 at this rate to rationalize for the correct ride and look. AR says 6 months before the gray centered 17's come out. I cannot wait. I am running Centelines now and the only reason I want o change is I do not want chrome wheels, hence my hesitation to get TT 2's. They just seem to be everywhere on everybody's car.

I will e-mail you a picture of my present set up. I wish I could figure out how to post it here. Maybe I am crazy and should well enough alone and not try to tuck the rears in a bit and the fronts out a bit. Let me know your thoughts on teh present set up. Thanks BRAD
BradB is offline  
post #15 of 23 (permalink) Old Mar 5th, 01, 02:25 AM
 
Join Date: Dec 2000
Location: New York, NY
Posts: 28
Post

NASTY, NASTY CAR. Looks great. It's amazing we all work on our cars and think they are amazing and you see other people's work and ideas and can really appreciate a nasty car. If I could only figure out how to post my car. Good luck.Orange and black houndstooth interior going in? <BLOCKQUOTE>quote:</font><HR>Originally posted by jenndon:
Go for 18's!!!!
i just posted a pic of our 69 in the exchange...under my toy, check it out and let me know what you think
<HR></BLOCKQUOTE>

BradB is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Team Camaro Tech forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address.
NOTE we receive a lot of registrations with bad email addresses. IF you do not receive your confirmation email you will not be able to post. contact support and we will try and help.
Be sure you enter a valid email address and check your spam folder as well.



Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome