Another wheel and tire thread

[72RustBucket]

I know there are tons of threads, and I have read through them all. I'm pretty sure I know the answer but would love clarification. I came across a matching set of centerline wheels like mine but wider. I'm thinking of picking them up but want to be sure.

They are 15x10 with 5 inches backspace.  Am I correct in thinking these will fit? I'm guessing a 275 will fit fine and a 295 will possibly rub on quarter?

Or I could go with Mickey Thompson ?

[MC1of80]

Doesn't matter on the tire manufacturer. All basically the same dimensions for the same size tires. The 5 inch backspacing is your issue. Even with a 275 you will most likely rub bad on the quarter panels. My son has a 275/60r15 on a 15x10 rim with 5 1/2" backspacing. 

[72RustBucket]

Thanks for the pictures! So the wheels themselves shouldn't be a problem? I mentioned Mickey Thompson because the sizing is different. 275/60 r15 is 10.8 inches wide 28 tall ,where I can get MT in 28x10 or 10.5...

 

Also, both of my quarters are bad, especially around the lip...so trimming them shouldn't be too much of a problem, though I'd rather not. 

[MCfan]

2 hours ago, 72RustBucket said:

They are 15x10 with 5 inches backspace.  Am I correct in thinking these will fit? I'm guessing a 275 will fit fine and a 295 will possibly rub on quarter?

Tom,

You are wise to search for answers to your questions regarding the fit of larger tires and wheels on the rear of our first gen Montes.  There are a lot of members here who have trial and error experience that are also willing share what they have learned.  But, there are also some excellent on-line tire size comparison tools and wheel offset calculators that will give you exact dimensional and visual comparisons for just about any combination you can imagine.

I can recommend the Tiresizer.com site because their size comparison tool (https://tiresize.com/comparison/) and wheel offset calculator (https://tiresize.com/wheel-offset-calculator/) are both easy to use and give  precise and highly visible results.  There really is no need to ever guess or assume that some alternative tire/wheel combination will fit or not fit if you have a known starting point for your comparisons.  By known starting point, I suggest getting (not guessing) the specific information of the tire/wheel combo you currently have installed on the rear of your Monte. 

For the wheel/rim, you need to know:
1. the bead mounting width (i.e. 6", 7", 8" etc.), Note: the actual rim width lip edge to lip edge is usually 1" greater which matters
2. the bead diameter (i.e. 14", 15" 17" etc.), the size of the tire mounted on your rim will tell you that (i.e. 275/60 - 15) 
3. the backspace (i.e. 4", 4.5", 5" etc). which is the distance between the wheel mounting surface and the inside rim lip edge
Example: If you have a 15 X 7 rim with the wheel mounting surface exactly centered, the backspace is (7+1)/2 = 4 inches (not 3.5")
It is best to measure the backspace by removing the tire/wheel, laying it face down, putting a straightedge across the inside rim lip (not the tire) and measuring down to the mounting surface.

For the tire you just need to know the size stamped on the side: tread width/series - bead diameter (i.e. 215/70-15)  Some old tires use letters for the tread width that must be converted to millimeters for the tire comparison tool.

Now look closely at the amount of clearance between the tire sidewall of your current combo and the inside of your quarter panel, especially at the lip of the wheel well opening. Measure it as closely and any way you can, even with hand/finger thickness - this will be critical in determining the backspace and offset needed for your new combo;

Once you have all of the information above for your known tire/wheel combo, you are ready to use the online tire sizer and wheel offset tools.

For the tire size comparison tool, just key the specs of your current tire into the Size 1 box and leave it alone.  Then key into the Size 2 box the specs of the tire you are considering.  Hit "compare" and it will give you the dimensional and visual comparison of the two tires including diameter (height), tread width, sidewall width, circumference, revs/mile, speedo correction, etc.

Now click on the blue text that says, "Looking to Compare Wheel Offset?"  If you have any question about the difference between offset and backspace, scroll down a bit and read their helpful definitions.  They are related terms but different measurements.

Key the tire and wheel specs from your known combo into the "Original Setup" boxes and the specs of the combo you are considering into the "New Setup" boxes.  It will immediately give you a visual and dimensional comparison.  Best of all it will tell you exactly how much closer you new larger combo will be to the top of your fender opening, inside frame/suspension and outside quarter panel.  If that combo uses up all of your available clearance, you will need to try increasing amounts of positive wheel offset to move the combo inboard.  Try different wheel offsets in the New Setup box until you see and read a safe amount of clearance with your quarter panel.  To get the corresponding backspace spec, just scroll down to the Wheel Offset/Backspacing Chart at the bottom and study it carefully.  Find your rim width and and chosen offset, then read the backspace at the top of that column above.

For example: The 10 inch rim you are considering with only a 5" backspace will move that wheel/tire combo a full 2" outboard toward your quarter panel.  Do you actually have that much clearance?  I doubt it ...  Even with a 5.5" backspace on that 10" rim the new wheel/tire combo will be 1.5" further outboard which may still be risky.  I am running a 275/60-15 on a 15x8 rim with 5.5" backspacing and can just insert fingers of a flat hand between the sidewall and the wheel well opening lip. 

Again, if you are comparing to a known combo currently mounted on your Monte, you will know how much new wheel/tire width you can safely move outboard and the rest will have to be moved inboard with positive wheel offset/backspace or you won't be going anywhere very fast.

I encourage you to give these online tools a try. Once you get the hang of it, you can compare a lot of possible combos and get the answers of what will work for you without taking any chances.  Good luck.

[72RustBucket]

Thanks for the reply. I've already used the comparison tool many times, but it doesn't help me visualize how they will look on our cars. 

[MCfan]

Sorry, I thought you were asking if they would fit not how they will look.

[MC1of80]

Tom, if you zoom in on the last pic, you will see very little space between the tire and what's left of the outer lip. The wheel wells are rotted on my son's Monte also. 

With the rim you mentioned, it will be 1/2" towards the wheel lip MORE than the one pictured on my son's Monte. 

Can you make it fit, sure. But will it be worth it? My "guesstimate" would be that you would have to trim the wheel lip flush with the outer quarter panel and it still MAY rub. 

Truly only one way to find out. You asked for opinions...

Eagerly await pics. 😁