4.5/6 drop and Tire sizes - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Mownsno · 08-21-2013, 01:34 PM

Is anyone running 255/45/20 front and 295/45/20 rear tires on 20x8.5 and 20x10 wheels. CC69Rat has been very helpful with sizing but I am thinking about running a 45 series instead of 40 series to fill out the wheel well a little bit more. Opinions?

magwakeenercew2jh · 08-21-2013, 01:57 PM

Quote:

Originally Posted by Mownsno

Is anyone running 255/45/20 front and 295/45/20 rear tires on 20x8.5 and 20x10 wheels. CC69Rat has been very helpful with sizing but I am thinking about running a 45 series instead of 40 series to fill out the wheel well a little bit more. Opinions?

Here are some stats with the same size wheels (width and diameter), but with a little smaller tires.

http://magwa.smugmug.com/Trucks/Stan...1122&k=SGZsV3h

I'd like to go a little bigger, so I'm watching the thread.

Mownsno · 08-21-2013, 02:30 PM

How much is your truck lowered?
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magwakeenercew2jh · 08-21-2013, 02:40 PM

Quote:

Originally Posted by Mownsno

How much is your truck lowered?
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Ahhhh! All the stats are listed in the captions on the pics in the link I posted.
The drop set up is captioned on the first pic.

4.5" in front and 6.0" in the rear.

CherokeeC10 · 08-21-2013, 02:49 PM

I only know this because I am looking at a 4/6 and have done a ton of research on this site so all credit goes to the previous posters on this subject, but seems that 275/40R20x10 w/ 5.5BS and 255/40R20x8.5 w/ 5.25BS is the perfect combo. You can go to a 295 rear but IMO it doesnt gain you a ton and since all trucks are made differently a 275 should be safer from rubbing. Also depends on if you have the wide or narrow rear end. Those specs are for the wide rear later model trucks. Hope this helps.

Mownsno · 08-21-2013, 03:33 PM

Quote:

Originally Posted by CherokeeC10

I only know this because I am looking at a 4/6 and have done a ton of research on this site so all credit goes to the previous posters on this subject, but seems that 275/40R20x10 w/ 5.5BS and 255/40R20x8.5 w/ 5.25BS is the perfect combo. You can go to a 295 rear but IMO it doesnt gain you a ton and since all trucks are made differently a 275 should be safer from rubbing. Also depends on if you have the wide or narrow rear end. Those specs are for the wide rear later model trucks. Hope this helps.

I have a 72 so yes its the wide rear end. I also have gotten the same B.S. numbers on the wheels. Just seeing if anyone has done this.
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67ctener · 08-21-2013, 03:06 PM

I think majority of people (including me) are running 255/40 up front and 295/40 out back. The toyo proxes stii seems to be a pretty popular tire around here. It's great proportion in my opinion with the 4/6 drop
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Mownsno · 08-21-2013, 03:38 PM

Quote:

Originally Posted by 67ctener

I think majority of people (including me) are running 255/40 up front and 295/40 out back. The toyo proxes stii seems to be a pretty popular tire around here. It's great proportion in my opinion with the 4/6 drop
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Agreed the Toyo's seem to be a popular choice. In fact JD wheel recommended Toyo's. $1694 to my door.
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bugmasta · 08-21-2013, 03:45 PM

Quote:

Originally Posted by 67ctener

I think majority of people (including me) are running 255/40 up front and 295/40 out back. The toyo proxes stii seems to be a pretty popular tire around here. It's great proportion in my opinion with the 4/6 drop
Posted via Mobile Device

same setup here. look and run great!

67ctener · 08-21-2013, 04:07 PM

Check out tire crawler. I had my toyos shipped for a little over $700. About 400 cheaper then my local tire store
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knomadd · 08-21-2013, 04:19 PM

I'm not certain but I think the OP was asking more for the 45 series sidewall vs a 40 series. Will a 295/45R20 fit, or will he need to stick with a 295/40R20? Unfortunately I don't know the answer to that question. I know it's taller and will effect your speedometer, but other than that I don't have any answers. I hope someone else can chime in on whether the 45 series will fit.

knomadd · 08-21-2013, 04:22 PM

I think, if 67ctener is right about majority of guys running 40 series rubber, you'll be safer sticking with that, or go with the 275/45 if you want more sidewall and clearance.

Mownsno · 08-21-2013, 04:42 PM

Quote:

Originally Posted by knomadd

I think, if 67ctener is right about majority of guys running 40 series rubber, you'll be safer sticking with that, or go with the 275/45 if you want more sidewall and clearance.

I agree that's what most people are running. I was looking for more tire height not a taller sidewall or more Clearance.
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knomadd · 08-21-2013, 05:29 PM

You probably know this, but just in case, the 40 and 45 numbers are a percentage of the width (295 mm vs 275 mm) so a 295/40R20 is approximately 29.3" tall while a 275/45R20 is approximately 29.75" tall. A 295/45R20 tire is about 30.45" tall.

Check this out... http://www.rimsntires.com/specs.jsp

**STP67-72** · 08-21-2013, 05:50 PM

I had about a 4.5 drop on my 72 and it buzzed the inner fenders with the taller 45 series on front. I think 4 inch might work.
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C_Ruiz · 08-21-2013, 06:48 PM

Quote:

Originally Posted by STP67-72

I had about a 4.5 drop on my 72 and it buzzed the inner fenders with the taller 45 series on front. I think 4 inch might work.
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I ran into the same issue as my friend here.
Had 255/45/20 up front on a 4.5/6 drop.
I now run 255/35/20 up front and 255/45//20 rear. Hope that helps.
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original-71 · 08-21-2013, 08:54 PM

What drop do you have
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original-71 · 08-21-2013, 09:04 PM

sorry just caught it talking to wife and kids and typing left me blind 40s are perfect IMOive seen them in person and fill fine. you can drop the rear 1/2 to 3/4 also with a drop block to get get that look you want
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CC69Rat · 08-21-2013, 08:51 PM

45s are possible but I pulled the backspacing back just a tad to make it work.

5 3/8 in the front 255/45/20 on an 8.5" wheel
5 5/8 in the rear 295/45/20 on a 10" wheel

.. yes, its splitting hairs but I thought it looked great. 255/40 is just a little dangerous for potholes and stuff IMO, I just like a little more sidewall.

You could also do 18s, same backspacing and your tire sidewalls would be a bit more meaty. Just a thought. SactoJims truck is awesome and hes running 18s. ( will be a little cheaper too )

Just thinking out loud..
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CC69Rat · 04-30-2017, 04:02 PM

This one has been around for a while, but just in case it might help someone. This is a 20x8.5 up front. 5.25" backspacing. 255/45/20. But this truck also has the 73-87 front member swap.

The rear is a 20x10, 5" backspacing 295/45/20. Narrow housing, 6" drop spring and 3 deg shim

No tailgate in this picture and other stuff still left to go on but this will give you an idea.

**67 cst swb** · 04-30-2017, 07:15 PM

Good info

jessemthompson · 04-30-2017, 07:41 PM

Anyone have opinions on toyo tires?

jessemthompson · 05-19-2017, 09:17 PM

255 40 20 up front and 295 40 20 in the rear.

08-21-2013, 01:34 PM	#1
Mownsno Registered User Join Date: Aug 2012 Location: Green Mountain Iowa Posts: 39	4.5/6 drop and Tire sizes Is anyone running 255/45/20 front and 295/45/20 rear tires on 20x8.5 and 20x10 wheels. CC69Rat has been very helpful with sizing but I am thinking about running a 45 series instead of 40 series to fill out the wheel well a little bit more. Opinions?

08-21-2013, 02:30 PM	#3
Mownsno Registered User Join Date: Aug 2012 Location: Green Mountain Iowa Posts: 39	Re: 4.5/6 drop and Tire sizes How much is your truck lowered? Posted via Mobile Device

08-21-2013, 02:49 PM	#5
CherokeeC10 Registered User Join Date: Aug 2013 Location: Tulsa, OK Posts: 24	Re: 4.5/6 drop and Tire sizes I only know this because I am looking at a 4/6 and have done a ton of research on this site so all credit goes to the previous posters on this subject, but seems that 275/40R20x10 w/ 5.5BS and 255/40R20x8.5 w/ 5.25BS is the perfect combo. You can go to a 295 rear but IMO it doesnt gain you a ton and since all trucks are made differently a 275 should be safer from rubbing. Also depends on if you have the wide or narrow rear end. Those specs are for the wide rear later model trucks. Hope this helps. __________________ And when he sees Saint Peter he will tell, "one more soldier reporting sir, for I have spent my time in hell".

08-21-2013, 03:06 PM	#7
67ctener Registered User Join Date: Oct 2012 Location: Arlington Washington Posts: 1,808	Re: 4.5/6 drop and Tire sizes I think majority of people (including me) are running 255/40 up front and 295/40 out back. The toyo proxes stii seems to be a pretty popular tire around here. It's great proportion in my opinion with the 4/6 drop Posted via Mobile Device __________________ Scott 67 c10 sold 89 c1500 90 k2500 91 s10 #chevyonly

08-21-2013, 04:07 PM	#10
67ctener Registered User Join Date: Oct 2012 Location: Arlington Washington Posts: 1,808	Re: 4.5/6 drop and Tire sizes Check out tire crawler. I had my toyos shipped for a little over $700. About 400 cheaper then my local tire store Posted via Mobile Device __________________ Scott 67 c10 sold 89 c1500 90 k2500 91 s10 #chevyonly

08-21-2013, 04:19 PM	#11
knomadd Registered User Join Date: Jul 2012 Location: Rosenberg, Texas Posts: 3,506	Re: 4.5/6 drop and Tire sizes I'm not certain but I think the OP was asking more for the 45 series sidewall vs a 40 series. Will a 295/45R20 fit, or will he need to stick with a 295/40R20? Unfortunately I don't know the answer to that question. I know it's taller and will effect your speedometer, but other than that I don't have any answers. I hope someone else can chime in on whether the 45 series will fit. __________________ -Duane C/10 Club Texas member 1971 Chevy C10 "Brutus" SWB Fleetside 2016 6.0L (L96) 6L90E (driver/project) 1965 Pontiac GTO "Royal Goat" 400/TH400 w/AC (my baby)

08-21-2013, 04:22 PM	#12
knomadd Registered User Join Date: Jul 2012 Location: Rosenberg, Texas Posts: 3,506	Re: 4.5/6 drop and Tire sizes I think, if 67ctener is right about majority of guys running 40 series rubber, you'll be safer sticking with that, or go with the 275/45 if you want more sidewall and clearance. __________________ -Duane C/10 Club Texas member 1971 Chevy C10 "Brutus" SWB Fleetside 2016 6.0L (L96) 6L90E (driver/project) 1965 Pontiac GTO "Royal Goat" 400/TH400 w/AC (my baby)

08-21-2013, 05:29 PM	#14
knomadd Registered User Join Date: Jul 2012 Location: Rosenberg, Texas Posts: 3,506	Re: 4.5/6 drop and Tire sizes You probably know this, but just in case, the 40 and 45 numbers are a percentage of the width (295 mm vs 275 mm) so a 295/40R20 is approximately 29.3" tall while a 275/45R20 is approximately 29.75" tall. A 295/45R20 tire is about 30.45" tall. Check this out... http://www.rimsntires.com/specs.jsp __________________ -Duane C/10 Club Texas member 1971 Chevy C10 "Brutus" SWB Fleetside 2016 6.0L (L96) 6L90E (driver/project) 1965 Pontiac GTO "Royal Goat" 400/TH400 w/AC (my baby) Last edited by knomadd; 08-21-2013 at 05:32 PM. Reason: wrong math...corrected

08-21-2013, 05:50 PM	#15
STP67-72 Senior Member Join Date: Jan 2002 Location: PORT NECHES, TEXAS / USA Posts: 1,667	Re: 4.5/6 drop and Tire sizes I had about a 4.5 drop on my 72 and it buzzed the inner fenders with the taller 45 series on front. I think 4 inch might work. Posted via Mobile Device __________________ 55 Chevy original swb (big back window) 61 Chevy bubble top (427-5 speed) 67 Chevy stepside (Krusty) 68 Chevy swb fleet (Lola) 68 Chevy swb fleet 71 Chevy swb fleet ( future PB project) 97 crew cab power stroke 07 SS Trail blazer

08-21-2013, 08:54 PM	#17
original-71 ///Relaxed Atmosphere Join Date: May 2010 Location: Houston,Tx Posts: 1,266	Re: 4.5/6 drop and Tire sizes What drop do you have Posted via Mobile Device __________________ 71-Cheyenne Super (E.C.E Static Drop 4.5/7". Intro Rally's 20X8.5 5" B.S 255/35/20 (F) 20X10 5.25 B.S 275/35/20 (R) 87-Silverado Static Drop 5/7" Raceline Explosion 5 22X8.5 (F) 22X10 (R) hector _________________________________ 1971 Chevrolet Cheyenne Super 1987 Chevrolet Silverado 2006 Ford Mustang GT 2012 Toyota 4-Runner 2014 Dodge Ram 1500 Sport Crew Cab

08-21-2013, 09:04 PM	#18
original-71 ///Relaxed Atmosphere Join Date: May 2010 Location: Houston,Tx Posts: 1,266	Re: 4.5/6 drop and Tire sizes sorry just caught it talking to wife and kids and typing left me blind 40s are perfect IMOive seen them in person and fill fine. you can drop the rear 1/2 to 3/4 also with a drop block to get get that look you want Posted via Mobile Device __________________ 71-Cheyenne Super (E.C.E Static Drop 4.5/7". Intro Rally's 20X8.5 5" B.S 255/35/20 (F) 20X10 5.25 B.S 275/35/20 (R) 87-Silverado Static Drop 5/7" Raceline Explosion 5 22X8.5 (F) 22X10 (R) hector _________________________________ 1971 Chevrolet Cheyenne Super 1987 Chevrolet Silverado 2006 Ford Mustang GT 2012 Toyota 4-Runner 2014 Dodge Ram 1500 Sport Crew Cab

08-21-2013, 08:51 PM	#19
CC69Rat Registered User Join Date: Jan 2011 Location: Chattanooga TN Posts: 6,210	Re: 4.5/6 drop and Tire sizes 45s are possible but I pulled the backspacing back just a tad to make it work. 5 3/8 in the front 255/45/20 on an 8.5" wheel 5 5/8 in the rear 295/45/20 on a 10" wheel .. yes, its splitting hairs but I thought it looked great. 255/40 is just a little dangerous for potholes and stuff IMO, I just like a little more sidewall. You could also do 18s, same backspacing and your tire sidewalls would be a bit more meaty. Just a thought. SactoJims truck is awesome and hes running 18s. ( will be a little cheaper too ) Just thinking out loud.. Posted via Mobile Device __________________ Chad 1967 C10 SWB - Project Savannah - 6.0/4L80 Currently underway 1968 C10 SWB - TOTY 2018, 50th Anniversary Tribute Project * Sold * Pride and Joy 1986 Silverado Short Fleet - Scarlet Sold 1985 Silverado Short Fleet Sold 2022 Jeep Gladiator Mojave 2001 Jeep Cherokee XJ 4x4 - Lifted, Built 1992 Jeep Cherokee XJ 4x4 - Lifted 2013 Honda Accord EX-L v6 Coupe 6spd (wife's ride)

04-30-2017, 04:02 PM	#20
CC69Rat Registered User Join Date: Jan 2011 Location: Chattanooga TN Posts: 6,210	Re: 4.5/6 drop and Tire sizes This one has been around for a while, but just in case it might help someone. This is a 20x8.5 up front. 5.25" backspacing. 255/45/20. But this truck also has the 73-87 front member swap. The rear is a 20x10, 5" backspacing 295/45/20. Narrow housing, 6" drop spring and 3 deg shim No tailgate in this picture and other stuff still left to go on but this will give you an idea. Attached Images __________________ Chad 1967 C10 SWB - Project Savannah - 6.0/4L80 Currently underway 1968 C10 SWB - TOTY 2018, 50th Anniversary Tribute Project * Sold * Pride and Joy 1986 Silverado Short Fleet - Scarlet Sold 1985 Silverado Short Fleet Sold 2022 Jeep Gladiator Mojave 2001 Jeep Cherokee XJ 4x4 - Lifted, Built 1992 Jeep Cherokee XJ 4x4 - Lifted 2013 Honda Accord EX-L v6 Coupe 6spd (wife's ride)

04-30-2017, 07:15 PM	#21
67 cst swb Senior Member Join Date: Nov 2001 Location: Rapid City, SD Posts: 2,281	Re: 4.5/6 drop and Tire sizes Good info __________________ My Trucks: 1967 Chevrolet Short Wide Box 327 TH350 9" w/3.90 gears paint will be White - Current Project 1967 Chevrolet Custom LWB 283 TH400 3.73 Posi, no-AC, no-PS, no-PB, bench-seat, small-window - mostly orig driver 1967 Chevrolet CST LWB originally a 327 TH400 3.73 Posi AC PS PB, had Buddy Buckets, Small Window - parts truck 1967 Chevrolet CST LWB, 283 MT 3.73 had Buddy Buckets, Panoramic Window - parts truck 2001 Chevrolet 3500 2WD Crew Cab Dually 8.1L Allison White

04-30-2017, 07:41 PM	#22
jessemthompson Registered User Join Date: Nov 2011 Location: Williamsburg, VA Posts: 960	Re: 4.5/6 drop and Tire sizes Anyone have opinions on toyo tires?



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05-19-2017, 09:17 PM	#23
jessemthompson Registered User Join Date: Nov 2011 Location: Williamsburg, VA Posts: 960	Re: 4.5/6 drop and Tire sizes 255 40 20 up front and 295 40 20 in the rear.

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