275s and 10.5 inch rims out back in 85?
- Thread starter SmockDoiley
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Well if you go to summitracing or jegs they give you the specs for each tire they sell like what the minimum and maximum rim widths you can use. I know I saw on the 245s that they recommend a 9 inch rim, but from the factory, Ford is using 245s on 8 inch rims. They recommend a 9-11 inch rim for a 275, and a 10.5-12.5 for the 315s. I didnt know they made those cobra rims in 10.5+.
Michael Yount
Mustang Master
A good rule of thumb is that you don't want the section width of the tire (225, 245, 275 -- those are section widths in mm) more than about 2-2.5" wider than the wheel. That approach provides the side wall support needed to keep the tread of the tire on the ground.
2" is good for narrower wheels; 2.5" for wider wheels.
So - 9" + 2.5" = 11.5" 11.5" X 25.4 mm/in = 292mm. So a 295 section tire is about as big as you'd want to run on a 9" wheel. You'd want at least a 10" wheel for a 315 tire. 9" is perfect for a 275. 8" is fine for a 245. In fact, many people run a 245 on a 7" wheel -- but it's probably not optimal.
2" is good for narrower wheels; 2.5" for wider wheels.
So - 9" + 2.5" = 11.5" 11.5" X 25.4 mm/in = 292mm. So a 295 section tire is about as big as you'd want to run on a 9" wheel. You'd want at least a 10" wheel for a 315 tire. 9" is perfect for a 275. 8" is fine for a 245. In fact, many people run a 245 on a 7" wheel -- but it's probably not optimal.
Yeah, I like the 10.5 inch rim due to the massive deep lip, and I've calculated the sizes and it should look just like a 245 on an 8 inch rim. I figured the 275 is 30 mms wider than a 245 and if you divide that by 25.4(mms in an inch) you get a little more than an inch wider tire and your adding close to that in rim width, so the 2 are about proportional. Now I just hope that these offsets supposedly designed for 94 and up, works with my 85. Usually its not a problem taking factory 8 inch rims off a newer car and putting them on an older car, but you throw that out the window when going with huge rims and weird offsets. Should work though, there isnt that much difference between the 2 models.
Nitto's run smaller than, say a BFG. That's why i can fit a nitto 315 on a 17X9. I don't believe a BFG would fit, they measure like a true 1-1 1/2" wider when you take a tape to them, even thou they are both 315/35. Different tire company=different real life measurements.
If it wasn't dark i'd go take a pic of the tire up close.
And here is a thread of mine goin on about my set up
http://forums.stangnet.com/showthread.php?t=599575
If it wasn't dark i'd go take a pic of the tire up close.
And here is a thread of mine goin on about my set up
http://forums.stangnet.com/showthread.php?t=599575
Michael Yount
Mustang Master
I suspect you'd have to use you one of them thar newfangled machines to pull the 315 off the rim..... 
You'd be amazed what you can mount on what (well, no GUY would be amazed at that). Just because it will physically mount doesn't mean it's optimum. People put too much tire on too little wheel all the time. You don't see the opposite very often -- most of the time when you see too LITTLE tire on too big of a rim it's the low rider set with skinnies mounted on an 8" wide gold-chromed wire wheel stuck out of the wheel well about 4"...
You'd be amazed what you can mount on what (well, no GUY would be amazed at that). Just because it will physically mount doesn't mean it's optimum. People put too much tire on too little wheel all the time. You don't see the opposite very often -- most of the time when you see too LITTLE tire on too big of a rim it's the low rider set with skinnies mounted on an 8" wide gold-chromed wire wheel stuck out of the wheel well about 4"...
393Bird
Founding Member
THOSE 315s look perfect on the 9 inch wheels. I have a set of 15 inch wheels being made to mount 275/50/15 MT on, so I will be removing my worn out BFG 275/40/17 DR, and trying a set of those 315s for street use. Look perfect.
Hu, Strange. So what do you guys think I should do for rim?? FR500s? or Bullitts? And what color? I was thinking not chrome because its too bling bling. My car is red with black hood stripe, and grayish blackish door trim, its an 85. So I thought it looked better with a painted rim, more mechanical and flat looking that way. Ive looked at the black bullitts, anthracite bullitts, black chrome bullitts, or anthracite FR500s, I like the graphite look, but I could just go with standard silver rims like how my 99 cobras are. What do you think.
Michael Yount
Mustang Master
Smock - I'm definitely a fan of the 'less bling'd wheels' look. Anything darker and flatter gets my vote. That's the approach I took with mine. They were originally silver -- but I carefully masked and sanded with 600 grit wet, then painted them with a metallic bronze, and then covered with Eastwood's satin clear. I'm pleased with the outcome and they've held up well - no chips/nicks in 2.5 years now.
http://www.stangcity.com/showphoto.php/photo/2242/cat/500/page/1
http://www.stangcity.com/showphoto.php/photo/2242/cat/500/page/1
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