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  15" wheel/tire heights?

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Author Topic:   15" wheel/tire heights?
sigtauenus
Gearhead

Posts: 1602
From: Beaufort, SC
Registered: Jun 2000

posted 03-29-2002 10:07 AM     Click Here to See the Profile for sigtauenus   Click Here to Email sigtauenus     Edit/Delete Message   Reply w/Quote
I found this rpm calculator,
http://www.ring-pinion.com/c-rpm_1.html

and put in some prospective choices for new axle gear ratios, and with my toploader, its not pretty at highway speed.

Right now my tires are 215x60R14, the rear is a 2.80, and at 70 mph that puts me at a little over 2800 rpm. (I'd calculate at 60 or 65mph, but gotta be realistic here).

If I upgrade the rear to 3.55 or so, and do nothing with the tires, that puts me at over 3600 rpm at 70 mph.

I'm planning on getting some new wheels one of these days and plan on either 15 or 16" wheels, but most likely 15". How tall are 60 and 70 series tires for 15" wheels? If I go with 3.55 gears and have, say, 26" tires, rpms at 70 drops to 3200. Still high, but not that bad, it'll probably mean I"ll drive it less on the highway.

Damn, there's so much to think about before you pick up the phone to order something.

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richard bohm
Gearhead

Posts: 370
From: tucson,az-luray,va
Registered: May 2001

posted 03-29-2002 10:26 AM     Click Here to See the Profile for richard bohm   Click Here to Email richard bohm     Edit/Delete Message   Reply w/Quote
my suggestion would be, if you want to drive the freeway, use a 225/60-15 tire and keep the 2.80 gears, or run the 3.55's with the above tire and an ovedrive trans. either way this puts your cruise rpm down below 2500.

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sigtauenus
Gearhead

Posts: 1602
From: Beaufort, SC
Registered: Jun 2000

posted 03-29-2002 10:36 AM     Click Here to See the Profile for sigtauenus   Click Here to Email sigtauenus     Edit/Delete Message   Reply w/Quote
I was thinking something similar, but if I don't put in lower gears, I'm almost wasting the effort to do the engine mods I'm planning.

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SteveLaRiviere
Administrator

Posts: 24286
From: Saco, Maine Toys: '70 Mustang Mach 1 - '72 Mustang Sprint - '94 F-150
Registered: May 99

posted 03-29-2002 02:21 PM     Click Here to See the Profile for SteveLaRiviere   Click Here to Email SteveLaRiviere     Edit/Delete Message   Reply w/Quote
That's why overdrives are so popular.

My Sprint sings with 4.30 gears and 26" tires!

------------------

'70 Mustang Mach 1 M code 351C 4V/FMX/3.25 open
'72 Mustang Sprint Coupe 351C 4V/FMX/4.30 Trac Lok
'94 F-150 XL 5.8L/E4OD/3.55 Limited Slip

MCA Member # 47773

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kcode
Gearhead

Posts: 2170
From: alvaton,ky,usa Suburb of Bowling Green, M&M #79, MCA #29208
Registered: Jun 99

posted 03-29-2002 03:47 PM     Click Here to See the Profile for kcode   Click Here to Email kcode     Edit/Delete Message   Reply w/Quote
Sam,
I can sympathize with you. I'm kinda faced with the same dilema. Just put new 225-60-15 Yokohamas on the coupe with the 3.89 rear, works real good with the 5-speed. But, I think I hurt the tranny at Atlanta and might have to put the unbreakable top loader back in. Good bye Overdrive.

Back in '70, used to run 4.56's in the Boss 302 on the street and wasn't afraid to do a 300 mile road trip at 4000 RPM. We must be getting soft in our old age when we worry about a cruisen RPM above 2500.

Mike

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sigtauenus
Gearhead

Posts: 1602
From: Beaufort, SC
Registered: Jun 2000

posted 03-29-2002 06:31 PM     Click Here to See the Profile for sigtauenus   Click Here to Email sigtauenus     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by kcode:
225-60-15 Yokohamas

Mike, what's the outer diameter of those 225-60-15's?

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kcode
Gearhead

Posts: 2170
From: alvaton,ky,usa Suburb of Bowling Green, M&M #79, MCA #29208
Registered: Jun 99

posted 03-30-2002 11:07 AM     Click Here to See the Profile for kcode   Click Here to Email kcode     Edit/Delete Message   Reply w/Quote
Sam,
They are listed as 25.6". I had BFG 215-65-15 on it before, they were 25.8". The Yoko do bite alot better.

Mike

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V8 Thumper
Gearhead

Posts: 1460
From: Orange, Ca. United States of America
Registered: Dec 2001

posted 03-30-2002 03:54 PM     Click Here to See the Profile for V8 Thumper   Click Here to Email V8 Thumper     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by kcode:
Sam,
... The Yoko do bite alot better.

Mike


Yea? I'm looking at BFG's, not sure I can stomach putting an 'asian' name on a sidewall


I don't mean to offend, just my $.02

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sigtauenus
Gearhead

Posts: 1602
From: Beaufort, SC
Registered: Jun 2000

posted 03-31-2002 08:47 AM     Click Here to See the Profile for sigtauenus   Click Here to Email sigtauenus     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by V8 Thumper:
not sure I can stomach putting an 'asian' name on a sidewall

how would that be different from the asian fender, bumper, or new instrument bezel? Guess only the obvious name, huh?

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