Jump to content

New shoes 😎


Recommended Posts

bill, nice looking tires ,from plainfield also a plumber ,now working for school district ,lots of members or non members in the area, roger

Link to comment
Share on other sites

I’m about to pull the trigger on a set of those myself. I’m trying to decide what size to go with on 8” Rallies. The previous owner put 235/60R15 on the front and 255/60R15 on the rear. I like the way they look, but the front will rub occasionally when turning and going over a small bump. There’s also signs that the driver’s side rear has previously rubbed the wheel well lip at some point. Any suggestions?

Link to comment
Share on other sites

The proper backspacing on the rim is important to having more clearance. On my 70 Monte I have 245/60s on four 15x8 Corvette rallys (4” backspacing) and they rubbed the quarter panel on one side. I had to bend the lip slightly for clearance. The fronts don’t rub but my car sits tall at stock height. When I had these wheels on my 72 years ago which was lower in the front end the front tires would rub occasionally. Ideally you want 4.5” or 6” backspacing for a 15x8 rim to fit nicely on these cars.

08463BC9-9A4F-40FE-AFFC-1B6100B4E801.jpeg

Link to comment
Share on other sites

19 hours ago, Canuck said:

I’ve seen three first gens in less than a week with new Cooper Cobras including mine. 🙂

Cooper Cobras on mine too,  your new tires look great...

Link to comment
Share on other sites

5 hours ago, sbarnette said:

I’m about to pull the trigger on a set of those myself. I’m trying to decide what size to go with on 8” Rallies. The previous owner put 235/60R15 on the front and 255/60R15 on the rear. I like the way they look, but the front will rub occasionally when turning and going over a small bump. There’s also signs that the driver’s side rear has previously rubbed the wheel well lip at some point. Any suggestions?

Sam,

Based on your comments above (and in agreement with Aaron's previous suggestion), I am almost certain that your particular 8" rallies have insufficient backspace (and positive offset) to run those 60 series tires on your first gen Monte. 

There is PLENTY of room inside the front and rear fenders of your Monte to accommodate those tires.  Many of us are running up to  255/60s on the front and 275/60s (or larger) on the rear with no rubbing issues BECAUSE we are using both 7 and 8 inch wide rims that have sufficient backspace (and positive offset) to position the wheel/tire combo safely within the wheel well. 

The reality is that where the web of a rim of any width mates to the front or rear wheel hub does not change relative to the wheel well frame or sheet metal so you have to move where the web of the rim is located within its width. That's what backspace and offset measurements are all about.

I'm guessing that if you want to use the rims you have now, you are going to significantly limit your tire size/series selection.  However, if you want to run a certain size/series of tire on a certain width of rim, you can easily determine how much backspace (and  positive offset) those rims will need to give you safe clearances by using the calculators on the tiresize.com website.  Just click on the Wheel Offset Calculator icon on the home page. 

That page has a great explanation of both backspace and offset because, while they are directly related, they are not the same measurement.  Car guys talk backspace (in inches) but almost all custom wheel manufacturers talk offset (in millimeters) so it is important to know the difference and how to convert from one to the other.  If you scroll to the bottom of the page in the Wheel Offset Calculator, you will see a cool table that converts backspace in inches to offset (negative, zero or positive) in millimeters for any size of rim you could possibly imagine. Here's that link: https://tiresize.com/wheel-offset-calculator/

For any width of rim, zero offset occurs when the web is exactly in the center of the wheel, however the backspace of that same rim is dependent on its exact width.  Example: for an 8" wide rim with zero offset, the backspace is 4.5" (NOT 4") because backspace is measured from the outside edge of the rim lip to the web.  Rim lips are almost universally 1/2" wider on each side of the tire bead width (8" in this case) so 8" bead width + 1" of lip width (both sides) is 9" divided in half (center of rim is zero offset) is 4.5".  Note that an 8" rim with a 5" backspace moves the web outward (wheel/tire combo inward) by 1/2" or 12 mm of positive offset from the centerline.  That is the kind of movement necessary to give adequate quarter panel clearance with larger/wider series tires on our Montes.

A 7" wide rim with zero offset has a backspace of 4" (7+1)/2 = 4.  To get positive offset on a 7" rim, backspace must be greater than 4".  In fact, the factory 7" wide rallies used on our Montes have a backspace of 4.30" or + 8mm offset.  Likewise, a 7" rim with 4.5" backspace has a +12 mm offset.

I suggest you measure the backspace on your current 8" rims, look up the offset in the online table and use that with the tire size you are considering in the Wheel Offset Calculator.  If nothing else, compare it directly to a stock 7" rim with 4.30" backspace and a near-stock tire size (which you know has adequate clearance).  You can then try various amounts of positive offset for an 8" rim to position your desired tire further inboard for adequate outboard clearance.  The table will tell you what the backspace measurement is for any offset (in 1/4" increments) so you will know what rim backspace you need for your larger/wider series tires.  Good luck.

Link to comment
Share on other sites

I'm running 275/60r15 on 15x8 rally wheels with 4.5 backspacing. My outer lip was trimmed slightly sometime in its life. I would recommend a 5 inch b.s. for a 15x8 and a 5.5 b.s. on a 15x10. 

Link to comment
Share on other sites

Thanks for all the replies. You guys confirmed what I have been thinking all along. I’m going to pull the wheels, check the backspacing and go from there. 😊

Link to comment
Share on other sites

16 minutes ago, Bill Henry said:

They are 245/60R15 on 15x7 rallies😎

Do you notice a difference in the speedo?? Did you have to change the speedo gear? Aaron put 255 60 on and you have 245 60. I'm trying to decide on which size to go with

Link to comment
Share on other sites

Actually, The tires that were on my car were way too tall to begin with, so putting these on there put the speedometer back where it should’ve been.

Link to comment
Share on other sites

My car has 225/70r15 which i think was close to the factory tire. I guess i will have to get someone to follow me when i get them changed out.

Thanks

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...