Bigger tires

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Logan R

I'm Awesome
Joined
Apr 10, 2023
Messages
124
Reaction score
64
Location
USA
Hey all I have a regular cab long box 2wd. I was wondering what is the biggest sized tires I can get with no clearance issues, and how do I adjust the speedo? The truck is meant to have 235/75R15’s on it and that’s what it has now. Thanks!
 

RichLo

E I E I O
Joined
Jan 6, 2015
Messages
3,618
Reaction score
5,540
Location
Wisconsin
285/75-16 is the general consensus for 4wd trucks, 305/70-16 if you are daring.

with a 2wd you'll need something to get the front higher to get those to fit. If your stuck on all stock, something with the same diameter/width as 275/75-16 converted to 15" wheels would be on the 'safe-ish' side of 2wd.

Check Tirerack.com for tire size charts to convert those sizes from 16" wheel to 15" wheel.
 

Nad_Yvalhosert

I'm Awesome
Joined
Oct 11, 2016
Messages
1,666
Reaction score
2,085
Location
Rochester, NY
I've seen 31x10.5r15 on 2wd trucks. Looks beefy. Pretty sure 32s are gonna rub.

As for the speedometer, you should regear the rear axle to compensate. My '95 C2500 got a 5" lift, 315s and 4.88 gears.
Numerically, I shouldve used something like a 4.25, so my speedo wasn't accurate. I found a remanned VSSB on eBay, modified with dipswitches so I could fine tune it now, and if I changed tire sizes in the future.
 

SentandBent4x4

I'm Awesome
Joined
May 17, 2023
Messages
122
Reaction score
149
Location
Kansas
31's rub at full lock, unless you get some offsets. Id level the truck if I were you.
 

Schurkey

Supporting Member
Supporting Member
Joined
Jan 14, 2018
Messages
10,963
Reaction score
13,743
Location
The Seasonally Frozen Wastelands
WHAT VEHICLE??? Speedo calibration varies with model year and perhaps other factors.

WHY do you need "bigger tires"?

Sounds like you're creating a bunch of headaches and reduced fuel economy and braking power, without having a benefit.
 

Logan R

I'm Awesome
Joined
Apr 10, 2023
Messages
124
Reaction score
64
Location
USA
It’s a 1990 c1500 with the 5.7 the reason I want bigger tires is I was wondering what the biggest I could run without clearance issues, as the current one look kinda small and I do plan on putting on a minimum of a 2 inch lift later down the road. So I figured if I ran the biggest tires the stock suspension could handle without rubbing then putting a 2+ inch lift wouldn’t make it look like it had donuts for tires then
 

someotherguy

I'm Awesome
Joined
Sep 28, 2013
Messages
9,789
Reaction score
14,143
Location
Houston TX
I'm with Schurkey on this one, but it's your truck, so...

Yeah, 31x10.50's do "fit" but you'll probably want to lift the front. If you're not ready to do your 2" lift just yet maybe get some 1" coil spacers as they're fairly cheap. Belltech makes some good ones that they include with their drop springs, but do sell them separately as well.

Recalibrating your speedometer is easy if you're reasonably competent with soldering on electronics. The DIP switch mod that 1992-1995 owners can do, you can do on a 1988-1991 as well, it's just a little bit more involved as you're pulling the cluster apart to get to it. There's a row of tiny fuses that the factory blows to "program" the cluster when built, they act as on/off jumpers, and you'll simply remove them and solder in a DIP switch. The chart for choosing your settings is different from the 1992-1995 stuff, and it's not as flexible overall, but IIRC 31x10.50 or an equivalent should be on that list.

I'll see if I can find my write-up on it and I'll edit back to link it here:
OK, couldn't find it on gmt400 so I re-wrote it from my old Chevytalk post (which was missing the pictures making it less useful)

Richard
 
Last edited:

Schurkey

Supporting Member
Supporting Member
Joined
Jan 14, 2018
Messages
10,963
Reaction score
13,743
Location
The Seasonally Frozen Wastelands
the reason I want bigger tires is I was wondering what the biggest I could run without clearance issues, as the current one look kinda small and I do plan on putting on a minimum of a 2 inch lift later down the road. So I figured if I ran the biggest tires the stock suspension could handle without rubbing then putting a 2+ inch lift wouldn’t make it look like it had donuts for tires then
So you want bigger tires and a lift because of vanity?

You seem to have absolutely no need to go through this hassle.
 
Top