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Old 08-21-2013, 01:34 PM   #1
Mownsno
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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?
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Old 08-21-2013, 01:57 PM   #2
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Re: 4.5/6 drop and Tire sizes

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Originally Posted by Mownsno View Post
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.
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Old 08-21-2013, 02:30 PM   #3
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Re: 4.5/6 drop and Tire sizes

How much is your truck lowered?
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Old 08-21-2013, 02:40 PM   #4
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Re: 4.5/6 drop and Tire sizes

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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.
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Old 08-21-2013, 02:49 PM   #5
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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.
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Old 08-21-2013, 03:06 PM   #6
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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
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Old 08-21-2013, 03:33 PM   #7
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Re: 4.5/6 drop and Tire sizes

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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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Old 08-21-2013, 03:38 PM   #8
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Re: 4.5/6 drop and Tire sizes

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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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Old 08-21-2013, 03:45 PM   #9
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Re: 4.5/6 drop and Tire sizes

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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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same setup here. look and run great!
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Old 08-21-2013, 04:07 PM   #10
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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
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Old 08-21-2013, 04:19 PM   #11
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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.
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Old 08-21-2013, 04:22 PM   #12
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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.
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Old 08-21-2013, 04:42 PM   #13
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Re: 4.5/6 drop and Tire sizes

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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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Old 08-21-2013, 05:29 PM   #14
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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
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Last edited by knomadd; 08-21-2013 at 05:32 PM. Reason: wrong math...corrected
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Old 08-21-2013, 05:50 PM   #15
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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.
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Old 08-21-2013, 06:48 PM   #16
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Re: 4.5/6 drop and Tire sizes

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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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Old 08-21-2013, 08:51 PM   #17
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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..
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Old 08-21-2013, 08:54 PM   #18
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Re: 4.5/6 drop and Tire sizes

What drop do you have
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Old 08-21-2013, 09:04 PM   #19
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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
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Old 04-30-2017, 11:07 AM   #20
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Re: 4.5/6 drop and Tire sizes

An old thread, but how do you guys like the toyo proxies?
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Old 04-30-2017, 04:02 PM   #21
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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.
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Old 04-30-2017, 07:15 PM   #22
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Re: 4.5/6 drop and Tire sizes

Good info
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Old 04-30-2017, 07:41 PM   #23
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Re: 4.5/6 drop and Tire sizes

Anyone have opinions on toyo tires?
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Old 05-19-2017, 09:17 PM   #24
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Re: 4.5/6 drop and Tire sizes

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





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