A slightly different front wheel question(s) - Team Camaro Tech
Wheels & Tires What fits what?

 1Likes
  • 1 Post By Larger Dave
 
LinkBack Thread Tools Display Modes
post #1 of 10 (permalink) Old May 2nd, 19, 06:25 PM Thread Starter
Gold Lifetime Member
Steve
 
Join Date: Apr 2002
Location: Southeast Pa.
Posts: 1,497
A slightly different front wheel question(s)

I am nearing the point where I must have front wheels and tires. I have DSE control arms and Wilwood 6 piston brakes. Those ought to move my wheels out 3/8. Common wisdom says I need a 5-1/8 backspace.
Ok. I made a gadget to check my wheel clearances and I think 8” 235’s will about make it when against the stops turned out. I don’t even have a backyard alignment or 3 fat guys sitting on the crossmember yet to compensate for the lack of engine but so far so good.
The questions. Some tire makers like nitro only list max width not section and tread. Is there a rule of thumb for tread width deduct when all you know is the max?
Offset v backspace. One could think that an 8” wheel with a 4” backspace would have a zero offset, but it doesn’t. Backspace is measured from the inner lip. Zero offset is either half the distance between the rim edges or the tire seating surface depending on whose illustration you follow. I looked at some wheels in my pile and there is nothing standard on lip dimensions. So is the -12 offset conversion number typically listed for a 8” wheel with a 4” backspace kind of a wag or am I missing something?

67RSSS......owned since 69. A basket case for most of it.
3d cad is offline  
Sponsored Links
Advertisement
 
post #2 of 10 (permalink) Old May 2nd, 19, 06:39 PM
Team Member
Don
 
Join Date: Jun 2006
Location: Mountain Springs, Texas
Posts: 3,458
Re: A slightly different front wheel question(s)

Maybe this will help:

https://rimsntires.com/specspro.jsp

I’m going to recommend against measuring for wheels with the suspension unloaded by the engine etc.

Don

1969 Camaro LSA 6L90E AME subframe and IRS
1969 Camaro vert LS3 4L65E Ridetech level 2 - sold
1959 El Camino project
1969 Mustang Sportsroof project
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

1956 Cameo project - C5 drivetrain
1957 Buick Caballero project
dhutton is offline  
post #3 of 10 (permalink) Old May 2nd, 19, 07:36 PM Thread Starter
Gold Lifetime Member
Steve
 
Join Date: Apr 2002
Location: Southeast Pa.
Posts: 1,497
Re: A slightly different front wheel question(s)

Thanks Don. That’s a nice interactive chart. I was fooling around with it tonight trying to figure out how to setup the gadget I made. I hope to get the passenger side sheet metal on this weekend then I’ll winch it down and look at it a little more seriously.

67RSSS......owned since 69. A basket case for most of it.
3d cad is offline  
 
post #4 of 10 (permalink) Old May 3rd, 19, 06:23 AM
Senior Tech
Dave
 
Join Date: Dec 2005
Location: Tampa, Florida
Posts: 4,602
Re: A slightly different front wheel question(s)

I use this cheap tool to answer theses questions:

https://www.summitracing.com/parts/php-01201

Big Dave
Larger Dave is offline  
post #5 of 10 (permalink) Old May 3rd, 19, 09:13 AM
DjD
Retired
Dennis
 
DjD's Avatar
 
Join Date: Apr 1999
Location: Fortuna, CA
Posts: 26,438
Garage
Re: A slightly different front wheel question(s)

Check the back spacing to offset chart on the link below. A GM 15x7 rally wheel has 4.25" of back spacing (+6 offset) and centers the wheel and tire in a '69 wheel well. That's stock with disc brakes up front but works well as a general guideline when fitting wheels on a '69. Brake conversions do have some effect on this. Is that 3/8" you mentioned based on drum or disc brakes? It will make a difference. An 8" wheel at +6 offset is 4.75" backspacing, I can't imagine 5 1/8" backspacing working with an 8" wheel.

I have a 17x8 4.75" bs with 235/45 17 tires (c5 vette conversion disc's) and it's close on the inside during tight corners.

https://www.rsracing.com/TechWheel.aspx

...Dennis

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


"Don't take life so serious, you won't get out alive..."
DjD is offline  
post #6 of 10 (permalink) Old May 3rd, 19, 11:47 AM Thread Starter
Gold Lifetime Member
Steve
 
Join Date: Apr 2002
Location: Southeast Pa.
Posts: 1,497
Re: A slightly different front wheel question(s)

Hey Dave, i made a gadget to do that job kinda. I saw the beefs about getting the wire right so i made a tool for myself. Not quite prime time but it will do.

Dennis. Wilwood says that their setup moves my mounting surface out 3/8”. On a 8” wheel that gets me to 5-1/8. You’re not the first to doubt. MCB did too and offered to send me the tool Dave was referring to but .....

67RSSS......owned since 69. A basket case for most of it.
3d cad is offline  
post #7 of 10 (permalink) Old May 3rd, 19, 01:52 PM
Senior Tech
 
Join Date: Nov 2018
Posts: 768
Re: A slightly different front wheel question(s)

Quote:
Originally Posted by 3d cad View Post
The questions. Some tire makers like nitro only list max width not section and tread. Is there a rule of thumb for tread width deduct when all you know is the max?
Try checking whatever tire you want on that manufacturers website. I found they have more "detailed" size 411
SoCal805 is offline  
post #8 of 10 (permalink) Old May 4th, 19, 07:00 AM
DjD
Retired
Dennis
 
DjD's Avatar
 
Join Date: Apr 1999
Location: Fortuna, CA
Posts: 26,438
Garage
Re: A slightly different front wheel question(s)

Quote:
Originally Posted by 3d cad View Post
Dennis. Wilwood says that their setup moves my mounting surface out 3/8”. On a 8” wheel that gets me to 5-1/8. You’re not the first to doubt. MCB did too and offered to send me the tool Dave was referring to but .....
Use a straight edge against the wheel mounting surface and measure the distance to the closest inward point of contact to see how much space you have to work with. You'll have to take the section width (Nitto's overall width) of the tire into play to prove it out.

...Dennis

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


"Don't take life so serious, you won't get out alive..."
DjD is offline  
post #9 of 10 (permalink) Old May 4th, 19, 07:40 AM
Senior Tech
Dave
 
Join Date: Dec 2005
Location: Tampa, Florida
Posts: 4,602
Re: A slightly different front wheel question(s)

Quote:
Originally Posted by SoCal805 View Post
Try checking whatever tire you want on that manufacturers website. I found they have more "detailed" size 411
Additionally the aspect ratio is the side wall height vs the overall tire height. Usually they list the tire height and the overall width can be used to set up a simple algebraic equation (=) to solve for the unknown.

And my high school students used to ask all the time when will we ever need to use this stuff?

Big Dave
Daddio65 likes this.
Larger Dave is offline  
post #10 of 10 (permalink) Old May 5th, 19, 12:28 PM Thread Starter
Gold Lifetime Member
Steve
 
Join Date: Apr 2002
Location: Southeast Pa.
Posts: 1,497
Re: A slightly different front wheel question(s)

what I made to check the clearance. Gotta winch the car down a little yet. That setup adds 3/8 to the mounting surface dimension
Attached Thumbnails
Click image for larger version

Name:	gadget1.jpg
Views:	10
Size:	136.1 KB
ID:	226807   Click image for larger version

Name:	gadget2.jpg
Views:	11
Size:	134.5 KB
ID:	226809  

67RSSS......owned since 69. A basket case for most of it.
3d cad 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



Similar Threads
Thread Thread Starter Forum Replies Last Post
MOMO Steering Wheel Project Redux 57vette Interiors 8 Aug 15th, 19 06:30 PM
Front end wheel clearance differences on 68 Camaro's... Shan Wheels & Tires 3 Apr 27th, 19 05:47 PM
Yet another front wheel question 3d cad Wheels & Tires 2 Nov 18th, 18 06:10 PM
EDIT MOMO Steering Wheel Project 57vette Edit Forum 17 Dec 28th, 17 06:14 AM
MOMO Steering Wheel Project 57vette Interiors 15 Nov 27th, 17 05:18 PM

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