Tire size in back
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Senior User
Joined: Jun 2003
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From: KS
Tire size in back
Hey everyone,
Maybe someone can help me by giving me some specs or advice. Ok, i have a 79 Ranchero with a 302 that ive put a lot of money into for power. In the front i have BFGoodrich Radial T/A's P225/60-15. I want some bigger tires in the back, but not huge. I have two choices, but i don't know which would be better. First of all, i have Summit's detroit locker in the back (disengages on turns) with 3.50 gears. Now the two choices i have are P245/60-15 or the P255/60-15. Now either way the diameter will be bigger and will make my truck tilt (its already stock like that, so im fine with it, i kinda like it) so that perspective doesnt matter. I was looking at the specs on the site, and the main difference other than diameter is in the Revolutions per mile and the max load. The 245 is 782 r.p.mile and the max load is 1753@35 psi, while the 255 is 768 r.p.mile and the max load is 1885@35 psi. Now since im looking for performance, i would want wider tires, but since its only 10 mm difference, it really doesnt matter. Im not sure though if the rev. per mile is suppose to be more or less (or close to the front which in this case is 813). If anyone can help me on this, i would appreciate it very much! Im not the greatest when it comes to tires. Thanks everyone!
Danny
P.S. - Thanks Ranchero77 for suggesting the 15's! My magnum 500 wheels only go up to 15, so i cant go any bigger, but still better than 14.
Maybe someone can help me by giving me some specs or advice. Ok, i have a 79 Ranchero with a 302 that ive put a lot of money into for power. In the front i have BFGoodrich Radial T/A's P225/60-15. I want some bigger tires in the back, but not huge. I have two choices, but i don't know which would be better. First of all, i have Summit's detroit locker in the back (disengages on turns) with 3.50 gears. Now the two choices i have are P245/60-15 or the P255/60-15. Now either way the diameter will be bigger and will make my truck tilt (its already stock like that, so im fine with it, i kinda like it) so that perspective doesnt matter. I was looking at the specs on the site, and the main difference other than diameter is in the Revolutions per mile and the max load. The 245 is 782 r.p.mile and the max load is 1753@35 psi, while the 255 is 768 r.p.mile and the max load is 1885@35 psi. Now since im looking for performance, i would want wider tires, but since its only 10 mm difference, it really doesnt matter. Im not sure though if the rev. per mile is suppose to be more or less (or close to the front which in this case is 813). If anyone can help me on this, i would appreciate it very much! Im not the greatest when it comes to tires. Thanks everyone!
Danny
P.S. - Thanks Ranchero77 for suggesting the 15's! My magnum 500 wheels only go up to 15, so i cant go any bigger, but still better than 14.
Senior User
Joined: Oct 2003
Posts: 347
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From: in a house
I'm glad the rim thing worked out for ya.
I wouldn' worry about the max load they are both well over a 1/4" of the GVW.
with those gears it looks like you would only loose about 55 rpm cruising between the two so I would say more meat to the street. I saw a 72 in PA running 295/55/15. he had about 3/4" clearance on the fender lip and to the frame. not sure if they would fit on a 15 x 8. maybe someone knows.
so how do you like the 3.50 gears vs stock? I still can't decide 3.50 or 3.70 for weekend drives and some race track fun.
if you or anyone is refinishing their magnum 500s here is a stencile kit http://www.jvbautosupplies.com/produ...oducts_id/3199
I wouldn' worry about the max load they are both well over a 1/4" of the GVW.
with those gears it looks like you would only loose about 55 rpm cruising between the two so I would say more meat to the street. I saw a 72 in PA running 295/55/15. he had about 3/4" clearance on the fender lip and to the frame. not sure if they would fit on a 15 x 8. maybe someone knows.
so how do you like the 3.50 gears vs stock? I still can't decide 3.50 or 3.70 for weekend drives and some race track fun.
if you or anyone is refinishing their magnum 500s here is a stencile kit http://www.jvbautosupplies.com/produ...oducts_id/3199
New User
Joined: Feb 2004
Posts: 11
Likes: 0
From: B'ham, Al
MAGNUM 500
Hey Danny,
Where did you get your Magnum 500's? I've decided to put them on my '79 as well, but still can't decide on size: 15x7 or 15x8? I have the stock 14" wheels now and dang thing looks like an ole ice cream truck.......I think you're ahead of me by a few months so I think I'll wait till you're done with the wheels & tires. May be I'll get to look at a pic or two before I fork out the $$$
Just ordered the intake, the carb and the headers yesterday...Still can't decide on the mufflers though....BTW do you know where to find some slotted valve covers?
Later...
Oz
Where did you get your Magnum 500's? I've decided to put them on my '79 as well, but still can't decide on size: 15x7 or 15x8? I have the stock 14" wheels now and dang thing looks like an ole ice cream truck.......I think you're ahead of me by a few months so I think I'll wait till you're done with the wheels & tires. May be I'll get to look at a pic or two before I fork out the $$$
Just ordered the intake, the carb and the headers yesterday...Still can't decide on the mufflers though....BTW do you know where to find some slotted valve covers?
Later...
Oz
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Senior User
Joined: Jun 2003
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From: KS
Hey Oz,
I got mine at Summitracing.com or from the catalog if you have it. They range from 122-129! Thats pretty good, and theyre chrome. If you want better ones, go to dearbornclassics.com and look up the wheels. Those are nice too. Same for the valve covers. Dearborn has some really good slotted valve covers that say 302 powered by ford or ranchero powered by ford. Also, summit has some more if you browse. BTW, i havent ordered the wheels yet, im still deciding on 15x7 or 8 too!!
Good luck
Danny
I got mine at Summitracing.com or from the catalog if you have it. They range from 122-129! Thats pretty good, and theyre chrome. If you want better ones, go to dearbornclassics.com and look up the wheels. Those are nice too. Same for the valve covers. Dearborn has some really good slotted valve covers that say 302 powered by ford or ranchero powered by ford. Also, summit has some more if you browse. BTW, i havent ordered the wheels yet, im still deciding on 15x7 or 8 too!!
Good luck
Danny
Senior User
Joined: Oct 2003
Posts: 347
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From: in a house
the 15 x 7 may not be recommended to accept the 255/60/15 you are considering. and while I'm sure they will still fit, some shops may not mount them for you. give your local tire guy a call to check.
New User
Joined: Feb 2004
Posts: 11
Likes: 0
From: B'ham, Al
Recommended tire size
Danny,
Just did some checking ...Goodyear recommends the following for their EAGLE #1 Nascar series..
255/60R15 approved rim width 7.0 - 9.0"
235/60R15 approved rim width 6.5 - 8.5"
225/60R15 approved rim width 6.0 - 8.0"
BF Goodrich has the exact same rim sizes listed as well for their T/A's...
My local guy whom I've known for the past 20 some odd years swears he would not go over 235 on a 15x7 but he will install them if I asked him to..He thinks as hot as it gets where I am in the summer (and knowing how I take a turn around the bend) it is not a good idea to have them.....
I think the safest thing to do is go with the 15x8's if you must have the 255's...
I'm still debating whether I should put 225 or 235's all around or make the rear's wider like you are planning to...
Later
Oz
Just did some checking ...Goodyear recommends the following for their EAGLE #1 Nascar series..
255/60R15 approved rim width 7.0 - 9.0"
235/60R15 approved rim width 6.5 - 8.5"
225/60R15 approved rim width 6.0 - 8.0"
BF Goodrich has the exact same rim sizes listed as well for their T/A's...
My local guy whom I've known for the past 20 some odd years swears he would not go over 235 on a 15x7 but he will install them if I asked him to..He thinks as hot as it gets where I am in the summer (and knowing how I take a turn around the bend) it is not a good idea to have them.....
I think the safest thing to do is go with the 15x8's if you must have the 255's...
I'm still debating whether I should put 225 or 235's all around or make the rear's wider like you are planning to...
Later
Oz
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