68 Stepside TIRE Question ??????

[ben88]

Hi Folks,

I have a 68 Stepside that I just converted the front end to disk using the front end from a 73 and Up, I also just put a 70 GTO Posi in the rear while also installing 3in drop springs. In addition, the wheel size I am using is 15x10. I am trying to get some good size meat's on the front and rear. I for sure want to use the same size tires front and back. I currently have 31x10.5x15 on the truck because thats what was on it before.

What are your suggestions for a good tire size to use that will look good but also be practical. Keep in mind I am a college student so the $$$$ is tight as always.

Any suggestions are completely welcomed and appreciated.

-Ben

[michael bustamante]

im going to use 295-50-15 on my 15x10
67 short stepper

[summitflier]

What is the back space on those 10 inchers?
Stock 68 width axle?

[ben88]

I like the 50's but the sidewall is to short for my taste. the GTO rear end is 1 in narrower, the backspacing on the wheels is 3.75 and then i am using lug pattern converters on each drum which adds 1 in to both sides.

[67ChevyRedneck]

You're not going to want 10" wheels on the front, (unless you want them to stick out past the fenders?) therefore you don't want or need the same size tires on the front.

You want to find a tire that compliments the wheel.

I'm putting 15x8 out back and 15x7's up front on my truck. I want a tire that's about the same size - height (with front being a bit smaller if need be), but want it to fit the different wheel sizes.

All wheels are approximately 1" wider than their "width." A 10" wheel is really 11", an 8" is really 9", a 7" is really 8", etc. Knowing that I'm going with 235/70/15 for the rear and 215/75/15 for the front. That gives me a 27.95" tire for the back and 27.7" for the front. My back tire will be about 9.25" wide and the front about 8.46 which are good sizes for my wheels.

Play with this calculator:

https://www.tacomaworld.com/tirecalc...0r15-215-75r15

Also use discounttire.com or similar for a price check as some tires sizes are a lot less common than others and therefore a lot more $$$.

[67ChevyRedneck]

So I was looking for a thread I posted in where someone had 10" wheels up front and they stuck out and rubbed the fenders to help you out... and it was yours

I'd keep your back spacing the same and get a set of 7 or 8" wheels for the front.

http://67-72chevytrucks.com/vboard/s...d.php?t=681891

Also, 31's aren't cheap. You may even be able to offset the cost of the front wheels by going with a smaller LT or P rated tire (which will be less expensive.)

[michael bustamante]

lookm at 325-60-15 in the rears then

[ben88]

He guys thank you for the response,

I see now that I should not have bought 10'' wheels for the front, unfortunately I did and I am not financially in the position to deal with that at the moment. With that being said I don't mind the tire sticking out a tad, i will deal with the hitting the fender issue. The 31's are huge tires and are to big but they don't hit anything when turning so i am confident that i can still use a large tire in the front.

[ben88]

Awesome calculator, Thank you so much

[OARNGESI]

275 60 15 is what i would go with all around 28 in tall so they should fill out nicely and get rid of your rubbing

[scoots71]

i have 295 50 15 all the way around 71 step

[CC69Rat]

Stepsides can be a challenge because of the rear fenders. You can get a little more tire under a fleetside.. BUT

Don't get me wrong, I love the steppers too. I have some advice for you but one thing we need to know is the width of the original rear end. Is that possible ? Do you still have it ?

The reason I'm asking is an original early housing is about 1.5" narrower than a later build housing. (70 and above) if you measure from the inside edge of one brake backing plate over to the other side.. how long is it?

Ex. If you had an original 71 housing it would be 57" from plate to plate. If it was an early housing it would be 55.5". Now we compare your GTO rear end at 1" shorter.. does that make it 56 or 54.5" long ?

Stuffing a 10" wheel under the stepper with 3.75" back spacing + 1" spacers you're technically running 2.75" backspacing. That means 7.25" + the bead on the wheel you'll have 7.5" beyond the mounting surface of the axle. That's a lot of wheel..

Any plans to lower this truck anytime soon?

Tire size works like this. Say 295/60/15.

295 ÷ 25.4 will give you the width of the tire in inches. You want something more than 10" wide (obviously)

Multiply the width x the aspect ratio.
295 ÷ 25.4 × .60 this gives you the height of the sidewall of the tires.

X2 - top of the tire + bottom of the tire

+ your rim size = overall height of the tire.

295 ÷ 25.4 x .60 x 2 + 15. Just adjust whatever your difference is to compare the sizes.

Let me know on your rear axle housing length and I can get you really close.

[Boog]

Originally Posted by ben88

I just converted the front end to disk using the front end from a 73 and Up, I also just put a 70 GTO Posi in the rear while also installing 3in drop springs. In addition, the wheel size I am using is 15x10. I am trying to get some good size meat's on the front and rear. I for sure want to use the same size tires front and back. I currently have 31x10.5x15 on the truck because thats what was on it before.
Any suggestions are completely welcomed and appreciated.
-Ben

I have a couple of questions.
Do you already have these 10" rims on the truck front and back? If not you have to know the bolt pattern is different, 5" C10 and 4 3/4" GTO.
If not already on the truck you can jack up one side in the rear and mount up one wheel then see and measure how well the wheel is centered in the fender. Then decide what tire size will fit the best. Go to Tire Rack or others websites and shop there. It gives you each tire's complete specs, treadwidth, diameter, etc. Easy enough.

[Mike C]

You may want to back up on some of this or at least wait until you have a little more $. Tire choices are limited with 15's compared to 17's

On my '69 short step I wanted a big of wheel as possible in the rear and zero clearance issues in the front. I dropped 4 1/2" front with 2.5" disc conversion spindles and 2" springs. I have 235 55 17 on 17x8 4.5" bs rims.

In the rear I did an housing flip (leaf spring truck) for a 7" drop. I went to the wider 71-72 5 lug rear and ran 275 55 17 on 17x9 with 5" bs.

This is pretty much the widest tire that will fit on a lowered stepside truck.

[ben88]

Thank so much for all the replies guys. I will get the measurements of the rear end for you tomorrow morning plus some pictures. I already have these wheels on the truck, currently I have no clearance Issues in the back or the front. However, the front fenders do hit the top of my tire when I hit a decent size bump. I need to decrease the tire sidewall size in the front to give me a bit more clearance. The reason I have " Spacers " in the back is because they are actually bolt patter converters that change my bolt pattern from the GTO patter to the Chevy pattern. I also put 3-inch drop springs in the rear which came out nicely. When i converted the front end to disk it for some reason resulted in my front being lower than before.

[ben88]

I will post a Picture of the truck in the morning to show that the front is unfortunetly higher 1" and i need to also deal with that somehow. But one thing at a time.