Quick question on rear tire size options

[Daddy64]

I have a chance to buy some 275/60-15 like new. Will they fit on the rear of my 64 fleetside that is lowered about 3-4 inches? I am more worried about the width than the height.
Thanks HB

[1restorick]

Sir, as long as the rearend is centered (adjustable panhard bar) and your wheels have the right offset, a 275-60-15" should fit without rubbing. I ran a 255-60-15" on the Blazer rally wheels on my 63 for years and could have easily gone larger. This was on a Fleetside. I have no experience with a stepside truck. Best of luck.

[TimE]

I ran 295/50-15s on the rear of my 64 step with a 3"/4" drop with no issues. The rims were old white spokes-not sure on backspacing. No adjustable panhard either.

[Daddy64]

Thanks guys, I pretty much knew they would fit. Just wanted some input before I spend the money on something I can't return.

[billydonn]

Originally Posted by TimE

I ran 295/50-15s on the rear of my 64 step with a 3"/4" drop with no issues. The rims were old white spokes-not sure on backspacing. No adjustable panhard either.

That surprises me on a stepside. 255/60-17 is very tight fit under mine, also lowered 3 to 4 inches. These are mounted on 8 inch wide TT2s. Most people think my tires are fatter than 255, so perhaps the tire width measurements are not perfectly consistent from brand to brand... just a guess. Well the question was about a fleetside so maybe its not a big deal. I just had to mention it though.

Edit: the answer may be tire diameter your 295 has 26.6 diameter... my 255 has over 29 inch diameter.

http://www.net-comber.com/tirecalc.html

[blackedoutharley]

Tire dimensions do vary slightly from one mfg to another. Also the specs shown for a given tire, by said mfg, are based on a specific measured rim width.

Cooper for example may show that a 275/60R15 has a section width of 11.1 " on a 8.5" wheel. The measured rim is shown in () in the section that shows the allowable rim width range (min to max width) that the tire is designed to be mounted on.

But also know that every .5" change in rim width changes section width .2" regardless of mfg.

So that tire with a section width of 11.1" on an 8.5" wheel will have an effective section width of 10.9" when mounted on an 8" wheel.

The numbers on a tire (in case anybody wants to know) are:

275= the section width (widest portion at the bubble of sidewall) as measured in MM's.

60= is the aspect ratio meaning that the sidewall height represents approx 60% of the above mentioned width. (Contrary to popular belief this number is not the width)

R= Radial; B= bias or bias belted; D= Diagonal belted etc....

There are so many variations but the sizing numbers are universal (for the most part. Europe has some crazy sizing but it doesn't apply to our uses).

[mr48chev]

I think the key is don't go over an 8 or 8.5 wheel. Leave the 10 inchers to the 4X guys. also on these trucks you don't want too tall a tire on the front or it doesn't look right. 275"s on the back and maybe 245/255 on the front.

Billydonn's Wheel/tire combo looks great.

[Daddy64]

48, I have 8" rims and the tires are BFG. I agree with the smaller on the front. Right now I have 235/60 on the front. I believe once I get the rearend centered and the bed centered there should be no problems.
Thanks

[oldblu65]

daddy64 , I have a ' 65 stepside that has 275/60/15 's on the rear . They are on an 8 inch wheel . They come very close to the lip on the fender as well as the inner bedside , this is at stock height . They do occasionally rub on one or both places depending on load in bed as well as how hard you're throwing the truck around . When I replace the tires , I'm going to go to a 255/70/15 on the rear for a little more height and clearance . Some tires , by different manufacturers , do differ somewhat in width as well as height. You might check around and see how they compare .

[billydonn]

Originally Posted by mr48chev

I think the key is don't go over an 8 or 8.5 wheel. Leave the 10 inchers to the 4X guys. also on these trucks you don't want too tall a tire on the front or it doesn't look right. 275"s on the back and maybe 245/255 on the front.

Billydonn's Wheel/tire combo looks great.

You are clearly a person of taste! And I agree that smalller tires look much better on the front. Posts above seem to support my idea that 295s would be risky under a stepside, don't you think?

[poorboy]

I have 275/60's on the 63 with a 72 rearend. They rub just a little bit since the rearend is wider. So I have to roll the lip a little.

[TimE]

Originally Posted by billydonn

You are clearly a person of taste! And I agree that smalller tires look much better on the front. Posts above seem to support my idea that 295s would be risky under a stepside, don't you think?

All I was posting was my personal experience with the 295s. It worked for my application. My truck was not super low but the tires did not hang out either. I had 235/60s front with the 295/50s in the rear. I ran the truck this way for several months with no issues. I guess my truck was atypical for one reason or another.
I also like the way your rim/tire combo looks on your truck, Billydon.

[blackedoutharley]

The 15"X8" wheel is the most common width wheel manufactured; 8.5" wheels surely exist but not as many choices. Most (not all) 15"X8" wheels will have approxiametly 3.75" - 4.0" of backspacing.

I currently have on my '65 LWB Fleet 15"X8" with 3.75" back spacing and run 31X10.50R15 tires at all four corners. This set up was great as I formerly had a 2800lb + 8' cabover camper on the truck and needed the extra load capacity the 6 ply (load range 'C') tire offered.

Prior to this I had the same wheels with 285/70R15 (same basic dimensions as the current tire) on the back and 255/70R15 on the front.

When considering tire sizes it is most important to check out the load capacity of the tire (and the wheel in very heavy applications) you want to run. Also consider and honestly answer "will I ever carry a heavy load in this?".

A 235/60R15 (26.1" dia) has a load capacity of 1642 lbs @ 44 psi. Remember that this is the maximum amount of weight that each tire can carry at max air pressure. This tire size is a direct replacement for early 70's to mid 90's Camaro/Firebird; does that sound like the right size tire for a truck (other than an S-10)?

You would only run that much air if the tire was carrying that much weight though; to do so otherwise would accelerate the wear factor in the center of the tread.

By comparision a 275/60R15 (28.0" dia) has a load capacity of 2149 lbs @ 44 psi. While the 255/70R15 (28.95" dia) can carry 2183 @ 44 psi.

While sizing and stance are visually important the tires ability to effectively carry any potential load is more important. Match the load with the dimensions desired to the application and you will have many years of service from the tires (assuming all other things are good).

Don't overload or under inflate tires!

p.s. on a SWB, either step or fleet a 15X8 wheel front and back with 255/60R15's (27.0") and 275/60R15's (28.0") in my opinion is just about perfect and if its moderately lowered does a near perfect job of filling the fenderwell nicely while still having enough load capacity (3770 lbs on front axle; 4300 lbs on rear).
For this set up I would run 33-35 psi in the front and about 30-32 in the rear unloaded (set air pressure on cold tires).

Lastly, if you are running alloy wheels on factory hubs/axles with the original 7/16" studs invest in a complete set of "ET Conical" lug nuts. They will, by their design, give you more thread engagement which is critical as the studs are short.
Here is an example of the lug nut. At about $1.50 each they are money well spent.
http://lug-nuts.net/index.php?main_p...roducts_id=222

The link shows a metric version but they are currently made in the required 7/16".

Sorry for the long winded tire lesson
All the dimensions are taken directly from Cooper Tires 2008 data book. The numbers should be very close if not exact to other tire mfg's.

[Daddy64]

If I get them on this weekend, I will post some pics. Everyone have a great weekend. HB

[fchava]

here is mine with a 275/60/15 on a 10" rim