Yet another rim/tire question.... - The 1947 - Present Chevrolet & GMC Truck Message Board Network

75BeauJames · 02-12-2004, 04:37 PM

Ok, I've exhausted the search feature over and over and keep getting myself more confused. Wanna put a new set of rims on the 'James, and I found some I like that are 17X8 5-5 14. I know the 17x8 part will work, I know that 5-5 is the bolt patter which will work too, but I'm confused about the offset.

I used the following formula and came up with a backspace of 4.8"

mm offset / 25.4 = Offset in inches
Rim Width / 2 = Centerline
Centerline + Offset + Rim Lip = Backspacing

So....

14mm / 25.4 = .55"
8 / 2 = 4"
4" + .55" + .25 = 4.8" Backspacing

Can someone confirm this is right and will work on the truck? Also I plan on running 255/60/17's up front and 275/60/17's out back. Think it'll look alright? Has to be better than white spray painted hubs on 4 mismatched tires! :p

Scott

**swervin ervin** · 02-12-2004, 08:47 PM

What's the .25 for? I think you are right on the 14mm since the offset is always listed in mm's, and I know the 25.4 is right. So, to be technical, and call it as I see it, I'm guessing they have 4.5" of BS. Which is .5" more than stock (4"). Either I'm right on the 4.5" or I'm wrong and they might be 5" of BS.

Can you not find out the BS of the wheels? Oh, also it the offset positive or negative? (In or out)

75BeauJames · 02-12-2004, 10:12 PM

The formula I used is on this page, and says to also calculate in the lip of the rim, and suggest .25", which I assume is over exadurated just for good measure.

Discount Tire's web site only lists the rims with a 14mm backspacing. In checking out other rims, I did notice a few that denoted a negative number (i.e. -7mm) so I assume the 14mm backspacing is with a positive offset.

I called down there and asked if they would fit, and of course the guy said no problem, and then asked me for my credit card number.

I'm not sure if he was just trying to make the sale or not, but he did state they would order the correct size if these didn't fit.

Crossing my fingers...
Scott

**swervin ervin** · 02-12-2004, 11:37 PM

You said, 14mm backspacing, but I'm guessing you are meaning to say offset, correct?

It's very strange that they can't tell you what the backspacing is. I've never seen a wheel listed that didn't tell this. Have you tried going to the wheel manufacturers site to see if you can find more info?

Oh, and never believe what someone at the place selling stuff tells you. You are right, they are trying to make the sell. I live by the addage of believing none of what I hear and a little less than half of what I see.

Mike

TIMSPEED · 02-12-2004, 11:39 PM

75,
in the front you'll wanna run a 255/55 17" tire ($80 from TireRack) and on the back run a set of 275/50 17's (Nitto's, seen them at Big O tire) That way, you'll have 28" tires all around.

75BeauJames · 02-12-2004, 11:53 PM

Quote:

Originally posted by TIMSPEED
75,
in the front you'll wanna run a 255/55 17" tire ($80 from TireRack) and on the back run a set of 275/50 17's (Nitto's, seen them at Big O tire) That way, you'll have 28" tires all around.

I ordered 255/60/17's for the front and 275/60/17's. Will the 60's still work?

TIMSPEED · 02-12-2004, 11:57 PM

Quote:

Originally posted by 75BeauJames
I ordered 255/60/17's for the front and 275/60/17's. Will the 60's still work?

Yeah, but you're going to have basically stock heighth tires (29"). You'll be ok with a 3/5 drop...but no more than that.

75BeauJames · 02-13-2004, 12:25 AM

That's okay, I've comitted myself to not going any lower than that until I can afford bags. My last truck, an 85 S-10, would get stuck on speed bumps and would teeter-totter until I could find a person or two to sit on the tailget for traction.

So that'll be at least towards the end of summer and I'll pickup a new rubber then. I just recently rescued the Beau James from a farm, and it won't pass inspection with the three bald mis-matched tires, so I just need something half-ass respectable that'll pass.

Scott

02-12-2004, 04:37 PM	#1
75BeauJames Registered User Join Date: Jan 2004 Location: Austin, TX Posts: 29	Yet another rim/tire question.... Ok, I've exhausted the search feature over and over and keep getting myself more confused. Wanna put a new set of rims on the 'James, and I found some I like that are 17X8 5-5 14. I know the 17x8 part will work, I know that 5-5 is the bolt patter which will work too, but I'm confused about the offset. I used the following formula and came up with a backspace of 4.8" mm offset / 25.4 = Offset in inches Rim Width / 2 = Centerline Centerline + Offset + Rim Lip = Backspacing So.... 14mm / 25.4 = .55" 8 / 2 = 4" 4" + .55" + .25 = 4.8" Backspacing Can someone confirm this is right and will work on the truck? Also I plan on running 255/60/17's up front and 275/60/17's out back. Think it'll look alright? Has to be better than white spray painted hubs on 4 mismatched tires! :p Scott

02-12-2004, 08:47 PM	#2
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	What's the .25 for? I think you are right on the 14mm since the offset is always listed in mm's, and I know the 25.4 is right. So, to be technical, and call it as I see it, I'm guessing they have 4.5" of BS. Which is .5" more than stock (4"). Either I'm right on the 4.5" or I'm wrong and they might be 5" of BS. Can you not find out the BS of the wheels? Oh, also it the offset positive or negative? (In or out) __________________ Mike 1985 Chevy C-10

02-12-2004, 11:39 PM	#5
TIMSPEED Join Date: Jan 2003 Location: Modesto, CA Posts: 1,321	75, in the front you'll wanna run a 255/55 17" tire ($80 from TireRack) and on the back run a set of 275/50 17's (Nitto's, seen them at Big O tire) That way, you'll have 28" tires all around. __________________ I have a few cars... See Them Here

02-12-2004, 10:12 PM	#3
75BeauJames Registered User Join Date: Jan 2004 Location: Austin, TX Posts: 29	The formula I used is on this page, and says to also calculate in the lip of the rim, and suggest .25", which I assume is over exadurated just for good measure. Discount Tire's web site only lists the rims with a 14mm backspacing. In checking out other rims, I did notice a few that denoted a negative number (i.e. -7mm) so I assume the 14mm backspacing is with a positive offset. I called down there and asked if they would fit, and of course the guy said no problem, and then asked me for my credit card number. I'm not sure if he was just trying to make the sale or not, but he did state they would order the correct size if these didn't fit. Crossing my fingers... Scott

02-12-2004, 11:37 PM	#4
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	You said, 14mm backspacing, but I'm guessing you are meaning to say offset, correct? It's very strange that they can't tell you what the backspacing is. I've never seen a wheel listed that didn't tell this. Have you tried going to the wheel manufacturers site to see if you can find more info? Oh, and never believe what someone at the place selling stuff tells you. You are right, they are trying to make the sell. I live by the addage of believing none of what I hear and a little less than half of what I see. Mike

02-13-2004, 12:25 AM	#8
75BeauJames Registered User Join Date: Jan 2004 Location: Austin, TX Posts: 29	That's okay, I've comitted myself to not going any lower than that until I can afford bags. My last truck, an 85 S-10, would get stuck on speed bumps and would teeter-totter until I could find a person or two to sit on the tailget for traction. So that'll be at least towards the end of summer and I'll pickup a new rubber then. I just recently rescued the Beau James from a farm, and it won't pass inspection with the three bald mis-matched tires, so I just need something half-ass respectable that'll pass. Scott



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