what tire pressure on 12.5 x 35's

56 Ford · 04-20-2009, 04:39 PM

Hello guys, I am new to this forum today. Already picking up some tips. My son has a 1979 f-150 that we rebuilt frame up last year. 472 engine, c6(rebuilt ourselves) 4.56 gears, 35'' Thornbirds. I have been searching for a couple of hours and haven't found a thread that specifically adresses tire pressure on this setup with these tires. The truck weighs 5400# and is used mainly on the street. The max tire pressure is I think 34 but we have been running 20. Lots of rolling resistance! How much should we run or haw much CAN we run without severly affecting wear?
Thanks in advance.

chickenbone · 04-20-2009, 05:18 PM

Not sure if this will help, my company did a worldwide safety warning on tire pressure. Can't find the site we used, but this link i'll add can help a little...

Tire Tech Information - Air Pressure - Correct, Underinflated and Overinflated

Petersons 4 wheel drive did a great article on large tire pressure for off road trucks.

Try there off road forum.
<< link removed by mod >>

gmctrucks · 04-20-2009, 05:43 PM

Welcome and howdy from TEXAS I hope you hang around for a long time we all have ton's of fun here. I running 40psi on my 31" tires if I was you I would run more.

56 Ford · 04-20-2009, 05:46 PM

Thanks chickenbone and gmc. I was kind of hoping someone would say more. GMC; how wide are your tires? I kind of think width would make more difference than height?

chickenbone · 04-20-2009, 07:34 PM

I've got 18 inch on my F-250 and most of my other large trucks run 10r22.5
I also own a 89International that i use to move my lowboy. I'll post a few pics. Real sharp ole Truck. Was my Brother-in-laws for years. He used to run Tators outa North Carolina.

gmctrucks · 04-21-2009, 02:43 AM

I'm running 31x10.50R15 on a 10 inch wheels im speading the tires big times but I like my wheels.

k20_chevy · 04-21-2009, 06:28 AM

I run 40psi and I got 33x12.50x16 Super Swamper SSR's.

bradrhale · 04-21-2009, 06:32 AM

havent seen alot of people use thornbirds as mainly street so difficult to give an exact measurement. if the max tire pressure advertises 34, than i might go with 30 or 32.

Rago · 04-21-2009, 02:14 PM

I'm pretty sure max tire pressure on those tires are 45 psi. You might double check on the sidewall. I had some Interco's that I ran 33 psi on the street. That was with an S15 Jimmy, so I would imagine a heavier vehicle like yours would enjoy about 38-40 psi. 20 psi would be better suited when you're offroad.

56 Ford · 04-22-2009, 08:44 AM

I've been away from the computer for a couple of days, glad to see all the responses! I'll check that rated pressure again and adjust the pressure upward. Thanks for all the help.

04-20-2009, 04:39 PM	#1
56 Ford Junior Member Join Date: Apr 2009 Posts: 8	what tire pressure on 12.5 x 35's Hello guys, I am new to this forum today. Already picking up some tips. My son has a 1979 f-150 that we rebuilt frame up last year. 472 engine, c6(rebuilt ourselves) 4.56 gears, 35'' Thornbirds. I have been searching for a couple of hours and haven't found a thread that specifically adresses tire pressure on this setup with these tires. The truck weighs 5400# and is used mainly on the street. The max tire pressure is I think 34 but we have been running 20. Lots of rolling resistance! How much should we run or haw much CAN we run without severly affecting wear? Thanks in advance.

04-20-2009, 05:18 PM	#2
chickenbone Senior Member Join Date: Mar 2009 Location: South Jersey Posts: 58	Not sure if this will help, my company did a worldwide safety warning on tire pressure. Can't find the site we used, but this link i'll add can help a little... Tire Tech Information - Air Pressure - Correct, Underinflated and Overinflated Petersons 4 wheel drive did a great article on large tire pressure for off road trucks. Try there off road forum. << link removed by mod >> Last edited by bradrhale; 04-21-2009 at 06:29 AM. Reason: no related forum advertising allowed

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Tire Pressure VS. Temperature	merlin5577	General Truck Forum	2	12-28-2008 04:17 PM
Tire air pressure.	gmctrucks	GMC Truck Forum	5	12-18-2008 08:37 AM
33's or 35's	duckkiller0010	Chevy Truck Forum	3	08-14-2007 12:48 PM
Tire Pressure?	Walleyes4me	Chevy Truck Forum	2	08-03-2005 01:53 PM
Tire Pressure for snow driving	99SD	Ford Truck Forum	12	03-19-2005 07:31 PM

04-20-2009, 05:43 PM	#3
gmctrucks Senior Member Join Date: Nov 2006 Location: Houston,Texas Posts: 4,030	Welcome and howdy from TEXAS I hope you hang around for a long time we all have ton's of fun here. I running 40psi on my 31" tires if I was you I would run more.

04-20-2009, 05:46 PM	#4
56 Ford Junior Member Join Date: Apr 2009 Posts: 8	Thanks chickenbone and gmc. I was kind of hoping someone would say more. GMC; how wide are your tires? I kind of think width would make more difference than height?

04-20-2009, 07:34 PM	#5
chickenbone Senior Member Join Date: Mar 2009 Location: South Jersey Posts: 58	I've got 18 inch on my F-250 and most of my other large trucks run 10r22.5 I also own a 89International that i use to move my lowboy. I'll post a few pics. Real sharp ole Truck. Was my Brother-in-laws for years. He used to run Tators outa North Carolina.

04-21-2009, 02:43 AM	#6
gmctrucks Senior Member Join Date: Nov 2006 Location: Houston,Texas Posts: 4,030	I'm running 31x10.50R15 on a 10 inch wheels im speading the tires big times but I like my wheels.

04-21-2009, 06:28 AM	#7
k20_chevy Senior Member Join Date: Apr 2009 Location: Lorain Posts: 82	I run 40psi and I got 33x12.50x16 Super Swamper SSR's.

04-21-2009, 06:32 AM	#8
bradrhale Senior Moderator Join Date: Apr 2006 Location: Texas Posts: 8,014	havent seen alot of people use thornbirds as mainly street so difficult to give an exact measurement. if the max tire pressure advertises 34, than i might go with 30 or 32.

04-21-2009, 02:14 PM	#9
Rago Senior Member Join Date: Jan 2009 Posts: 76	I'm pretty sure max tire pressure on those tires are 45 psi. You might double check on the sidewall. I had some Interco's that I ran 33 psi on the street. That was with an S15 Jimmy, so I would imagine a heavier vehicle like yours would enjoy about 38-40 psi. 20 psi would be better suited when you're offroad.

04-22-2009, 08:44 AM	#10
56 Ford Junior Member Join Date: Apr 2009 Posts: 8	I've been away from the computer for a couple of days, glad to see all the responses! I'll check that rated pressure again and adjust the pressure upward. Thanks for all the help.