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73-87 Chevy _ GMC Trucks => Wheels & Tires => Topic started by: oldblue76 on October 30, 2015, 08:59:37 pm

Title: Bigger tire size
Post by: oldblue76 on October 30, 2015, 08:59:37 pm

I have a 76 Chevy K10. Currently has stock tires on it. I am needing to replace all tires and am wondering how big I can go on with stock wheel and stock ride hight thanks.

Title: Re: Bigger tire size
Post by: FlatBlack77 on October 31, 2015, 08:10:37 am

33x12.50r15s is about as big as you can go on stock 15x8 rally wheels without major trimming. they fit on my stock 79

Title: Re: Bigger tire size
Post by: roundhouse on October 31, 2015, 09:24:57 am

Yep 33x12.50 will fit fine on stock rally's on most trucks with no lift and no rubbing
Looks good too


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Title: Re: Bigger tire size
Post by: timthescarrd on October 31, 2015, 05:28:31 pm

There's a couple things to consider with this, If you off-road where your suspension is going to articulate very much anything above 31x10.5 is probably going to rub.  for mostly pavement driving then 33x12.5 should be fine.  If you springs have sagged considerably then 31x10.5 may even rub.  Also consider the drivetrain, what transmission and rear gear ratio do you have.  If you have 2.73 or 3.08 then larger tires tend to lug on steep hills or towing.

Title: Re: Bigger tire size
Post by: oldblue76 on October 31, 2015, 07:44:28 pm

I have the SM465 and I believe the owner before me (Wife's grandfather) put a different rear end on the truck to better on the highway. I havent had a chance to see what gear ratio is in the rear end. My front leaf springs have sagged.

Title: Re: Bigger tire size
Post by: enaberif on November 02, 2015, 09:24:41 am

You need to swap both front and rear gears in a 4wd.You can't just do the rear and be ok.

Might be time to check your diffs and gear ratios.

Title: Re: Bigger tire size
Post by: Irish_Alley on November 05, 2015, 11:30:27 pm

front "sag" is called negative arch and thats how they come
also check this out.
http://forum.73-87chevytrucks.com/smforum/index.php?topic=31301.0

Title: Re: Bigger tire size
Post by: ehjorten on December 04, 2015, 09:25:22 am

My '77 K20 is all stock suspension with the negative arch front springs as Irish just explained.  I have 31's on it that are the Toyo Open Country MTs.  I thought I had the actual P-Metric tire size on my phone, but I don't.  Anyways...the tires don't rub in the wheelwell, but I am certain 33's would if you actually used your suspension.  The side lugs on the tires will rub the drag-link a little at full lock.  31's are perfect for stock ride height on your truck.