15x7/8 tire size question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

cliffsta · 04-09-2005, 06:08 PM

Ok in the not too too distant future, I'm gonna buy some wheels. I already got them picked out (SO DON'T GIVE ME YOUR OPINION ON WHY YOU DISLIKE THEM PLEASE). Should I stick with 15x7, or go up to 15x8 (stock wheels are 15x7 right?)? If I go with 15x8, i wanna keep the same heighth tire (235 is the heighth right?)so the speedometer isn't whack.. so for the wider rim, wouldn't I want like, 235/ 85(?) / R15?

Thanks in advance,
cliff

screwballl · 04-09-2005, 07:12 PM

i was gonna say something like 31x10.50 if you dont mind... they look great on my 76...

boxrodz · 04-09-2005, 07:47 PM

Not quite.

In your example, 235 refers to the width of the tire (in millimeters) at its' widest point and not the height. The 85 refers to the ratio of the height with respect to the width. A 85 series tire is considered to have a very tall sidewall. I think the stock tires are 225/75/15 which are 28.29" tall (225*75*(2/2540)+15). To give you some flavor:
A 255/60/15 tire is 27.05" tall.
A 275/60/15 tire is 28" tall.
A 245/70/15 tire is 28.5" tall.
A 255/70/15 tire is 29.06" tall.
The 60 series tires are more popular than the sometimes uncommon 70 series tires.

Visit the tirerack to see what tires are available for the size tire you want to run. It'll also give you the tire specs (dimensions) and the recommended rim width for a given tire.

What kind of look are you after? Do you want to stick with the same size tires at all four corners? Are you planning on lowering (or raising) your truck in the future?

RockHQ · 04-09-2005, 08:01 PM

Most tires nowadays are marked with their contact pattern width (A), aspect ratio or tirewall height (B), and wheel diameter (C), to put it simply.

An example: 235 (A) / 75 (B)/ R15 (C)

Here we have a tire that has a 235mm nominal contact pattern width, aspect ratio of 75 and a rim diameter of 15 inches.

Aspect ratio determines the sidewall height of a tire, it's a percentage of the nominal contact pattern width. Regarding my example, an aspect ratio of 75 equals: 0.75*235= ~176 millimeters.

Another example: 275/60/R15

Contact pattern width is 275 millimetres, sidewall height is 165mm.

What that tells you, is that even though the 275/60R15 tire looks a lot bigger than the first example, it's actually smaller in diameter, yet wider.

If you intend to run skinny and tall tires such as the 235s, get 7 inch wheels. Low-profile, wider tires will look better on an 8" wheel. JMO.

[edit] damn, looks like i was typing too slowly

cliffsta · 04-09-2005, 10:38 PM

CRAP!! I knew i'd say it bass ackwards!!!!

What I ment to say is i want the same height tire as to keep the speedometer accurate, but maybe a wider contact patch.

So basically I want like a 245/70/15 maybe to keep the same height? This is assuming I go with 15x8.

If i go with the 15x7 i could of course go with the same size on their now (235/75/R15)

Thanks for the feedback! Im just now starting to understand all this.

No raising or lowering, stock height also if that helps, i just want a fitting tire that isn't stretched in or out too bad to fit.

MylilBowTie · 04-10-2005, 08:30 PM

31x10.50 fit real nice on 15x8s

Jonboy · 04-10-2005, 11:03 PM

275/60R15's look pretty nice on 8" wheels, and have about the same installed height as the 235's you have on your 7" wheels now.

**N2TRUX** · 04-10-2005, 11:20 PM

Go with an 8" wheel. No matter what tire you run, it will lay out fatter on an 8....

04-09-2005, 06:08 PM	#1
cliffsta Stepsides RULE Join Date: Jul 2004 Location: Pineville, LA Posts: 1,921	15x7/8 tire size question Ok in the not too too distant future, I'm gonna buy some wheels. I already got them picked out (SO DON'T GIVE ME YOUR OPINION ON WHY YOU DISLIKE THEM PLEASE). Should I stick with 15x7, or go up to 15x8 (stock wheels are 15x7 right?)? If I go with 15x8, i wanna keep the same heighth tire (235 is the heighth right?)so the speedometer isn't whack.. so for the wider rim, wouldn't I want like, 235/ 85(?) / R15? Thanks in advance, cliff __________________ 1981 Chevy C10 Custom Deluxe Stepside 350 V8, headers, side exhausts, 3-speed auto SOLD 1980 Chevy C10 Custum Deluxe Stepside 305 V8, Edelbrock Performer Intake, Edelbrock 1406 600CFM 4-barrel, TH350C. Bent rod. SOLD 1984 GMC Sierra Classic Longbed 6.2L Diesel SOLD 2009 Kawasaki KLX-250S too many mods for this signature 1999 Honda Accord EX 4-cylinder, 17" Motegi Wheels 215/45/17 Sumitomo tires, Tein S-Tech lowering springs, KYB GR2 shocks, Acura TL 20mm rear swaybar, debadged, blackhoused headlights, Short-Ram Intake Cardomain of the Accord

04-09-2005, 07:12 PM	#2
screwballl Tonawanda 454 Join Date: Mar 2004 Location: Liquid Sunshine State Posts: 2,754	i was gonna say something like 31x10.50 if you dont mind... they look great on my 76... __________________ 91 Chevy Suburban Tonawanda 454 R2500 - SOLD!!! 04 Dodge Durango 5.7L Hemi 2WD, 24K miles (as of July 2011) In the past 30 years about 90% of Fords are still on the road, the other 10% made it home. -------------------

04-09-2005, 07:47 PM	#3
boxrodz Until Seventy Times Seven Join Date: Feb 2005 Location: Rocky Mountain Front Range Posts: 1,301	Not quite. In your example, 235 refers to the width of the tire (in millimeters) at its' widest point and not the height. The 85 refers to the ratio of the height with respect to the width. A 85 series tire is considered to have a very tall sidewall. I think the stock tires are 225/75/15 which are 28.29" tall (22575(2/2540)+15). To give you some flavor: A 255/60/15 tire is 27.05" tall. A 275/60/15 tire is 28" tall. A 245/70/15 tire is 28.5" tall. A 255/70/15 tire is 29.06" tall. The 60 series tires are more popular than the sometimes uncommon 70 series tires. Visit the tirerack to see what tires are available for the size tire you want to run. It'll also give you the tire specs (dimensions) and the recommended rim width for a given tire. What kind of look are you after? Do you want to stick with the same size tires at all four corners? Are you planning on lowering (or raising) your truck in the future? __________________ boxRODz 1983 C10 SWB Fleetside When two halves is gone, there's nuthin left. Two nothings is nuthin. That's mathematics son. You can argue with me but you can't argue with figures. Two half nothings is a whole nuthin... Last edited by boxrodz; 04-09-2005 at 08:31 PM.

04-09-2005, 08:01 PM	#4
RockHQ ROCKET POWER! Join Date: Feb 2003 Location: Finland, Europe Posts: 509	Most tires nowadays are marked with their contact pattern width (A), aspect ratio or tirewall height (B), and wheel diameter (C), to put it simply. An example: 235 (A) / 75 (B)/ R15 (C) Here we have a tire that has a 235mm nominal contact pattern width, aspect ratio of 75 and a rim diameter of 15 inches. Aspect ratio determines the sidewall height of a tire, it's a percentage of the nominal contact pattern width. Regarding my example, an aspect ratio of 75 equals: 0.75235= ~176 millimeters. Another example: 275/60/R15 Contact pattern width is 275 millimetres, sidewall height is 165mm. What that tells you, is that even though the 275/60R15 tire looks a lot bigger than the first example, it's actually smaller in diameter, yet wider. If you intend to run skinny and tall tires such as the 235s, get 7 inch wheels. Low-profile, wider tires will look better on an 8" wheel. JMO. [edit] damn, looks like i was typing too slowly __________________ What did i do last nite? I had a wonderful time, That's what they tell me What did i do last nite? 1979 C-10 shortfleet: Olds 350, Th400, 12 bolt Current project: 1969 Olds 455 W-30, needing a rebuild Last edited by RockHQ; 04-09-2005 at 08:02 PM.*

04-09-2005, 10:38 PM	#5
cliffsta Stepsides RULE Join Date: Jul 2004 Location: Pineville, LA Posts: 1,921	CRAP!! I knew i'd say it bass ackwards!!!! What I ment to say is i want the same height tire as to keep the speedometer accurate, but maybe a wider contact patch. So basically I want like a 245/70/15 maybe to keep the same height? This is assuming I go with 15x8. If i go with the 15x7 i could of course go with the same size on their now (235/75/R15) Thanks for the feedback! Im just now starting to understand all this. No raising or lowering, stock height also if that helps, i just want a fitting tire that isn't stretched in or out too bad to fit. __________________ 1981 Chevy C10 Custom Deluxe Stepside 350 V8, headers, side exhausts, 3-speed auto SOLD 1980 Chevy C10 Custum Deluxe Stepside 305 V8, Edelbrock Performer Intake, Edelbrock 1406 600CFM 4-barrel, TH350C. Bent rod. SOLD 1984 GMC Sierra Classic Longbed 6.2L Diesel SOLD 2009 Kawasaki KLX-250S too many mods for this signature 1999 Honda Accord EX 4-cylinder, 17" Motegi Wheels 215/45/17 Sumitomo tires, Tein S-Tech lowering springs, KYB GR2 shocks, Acura TL 20mm rear swaybar, debadged, blackhoused headlights, Short-Ram Intake Cardomain of the Accord

04-10-2005, 08:30 PM	#6
MylilBowTie Right turn Clyde Join Date: Nov 2002 Location: Cincinnati, Ohio Posts: 2,911	31x10.50 fit real nice on 15x8s __________________ 1974 C25 LWB: 454 4bbl Carb / TH400 / 3.73 1992 Camaro RS 305 TBI

04-10-2005, 11:03 PM	#7
Jonboy Slots go on anything! Join Date: May 2003 Location: Richardson, TX Posts: 5,957	275/60R15's look pretty nice on 8" wheels, and have about the same installed height as the 235's you have on your 7" wheels now. __________________ 1974 Jimmy- 5.3/4L80e/NP241

04-10-2005, 11:20 PM	#8
N2TRUX Happy to be here Join Date: Mar 2000 Location: Cypress, TX Posts: 39,021	Go with an 8" wheel. No matter what tire you run, it will lay out fatter on an 8....



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