Steel Rally Rims & Tires -- Max and Proper Sizing

[1986swb]

I'm new to this forum and I'm sure someone has asked/answered a similar question regarding rally rims and tire sizing but I appreciate your experience and insights.

I have a 1986 GMC Sierra Classic SWB, 2WD. I currently have the stock 15" x 8" steel rally rims on the truck with truck tires: 235 x 75. The truck has a stock 305 H engine, rebuilt 700R tranny, and is bone stock in ride height and in features (full power everything, including cold AC).

I would like to change all 4 tires to passenger tires of either 255 or 275, 60series, but I don't know if 1) the height gap between the fender and tire will look too wierd (large like a 4WD) and 2) if I decide on the 275 sizing, will it fit neatly under the front fender wells.

Any insights is greatly appreciated

[old Rusty C10]

Hi welcome to the board... Im not sure about your question but bein youre new just wanted to welcome ya.. Im sure someone else who knows about these things will be able to answer your question
It would be nice if you could post some pics of your truck and your plans
I used to own an 86 but mine was a basic LWB custom deluxe with the 4.3 and th400

[Malo83]

If your gonna keep it at stock height you'll be alright with a 255/60 tire all around as well as the 275/60 tire but if you plan on dropping the truck in the future you'll have problems on the front end with a 275/60 tire rubbing.

[BowTieOgre]

I had 275/60/15s all around and when I lowered it (4.5/5) I had to replace the front tires with 245s. I like the way the 275s filled up the wheel well though. Here are some side shots of my Blazer at stock height and C10 with a 4.5/5" drop...both with 275/60/15.

[Malo83]

Nice Blazer and pickup

[68Timber]

Originally Posted by Malo83

If your gonna keep it at stock height you'll be alright with a 255/60 tire all around as well as the 275/60 tire but if you plan on dropping the truck in the future you'll have problems on the front end with a 275/60 tire rubbing.

I'm glad I saw this thread. I bought a set of Wheel Vintiques 15x10 rallys and had planned to run 275/60's all the way around with some drop. Not slammed, but maybe 2" just to close the fender to wheel gap a little. Will 275/60's rub with a small drop? Truck is a 79 2wd Blazer.

Thanks.

[Slonaker]

I would go with 255/70/15 or 275/60/15. Both will fit the 8" wheels well, and will look good in the wheelwells. They are about the same height.

I have 255/70/15 on mine, if you want to look through my gallery. There are pics of it there both lowered and stock with those tires.

http://www.slonaker.net/gallery/thumbnails.php?album=3

Slonaker

[1986swb]

Thanks everyone for your insights on tire sizing for 15" x 8" steel rallies. Based on all of the feedback, it has come down to either 255/70 or 275/60 series tires. Additionally, here is some info. that you probably already know about that has influenced my decision:

235/75/15: OD = 29" (with factory spec tires)
255/60/15: OD = 26.8"
255/70/15: OD = 29.1"
275/60/15: OD = 28"

OD = Overall Diameter

I'm still torn and I still need to be convinced on the tire size. For the time being, I plan to keep the ride height stock as the truck is a "work in progress." However, I still want a nice looking stance, even though the truck is basically stock.

Here are some older pics of my 1986 GMC SWB C1500 Sierra Classic. The rims are aftermarket aluminum 15" x 7" with 235/75/15 rubbers. When the sun comes out in Seattle, I'll take updated shots of the truck.

Thanks again everyone for your timely replies and insights.

- Steve.

[1986swb]

After much consideration, I am going with 255/70/15 sizing on 15" x 8" steel rallies, all around. Slonaker's pics detailed both the height and width of the tires as they sat in the fender wells at stock ride height.

Thanks again everyone. Now I can sleep!

Whew!

[chevymotocross]

I'm also going with 255/70/15 tires on my 87. The truck, currently at stock height, has 265/75/15 tires. They fill the wheel wells nicely but I want to do approximately a 3/4 drop and those tires will rub. I work at a tire shop and snagged 4 great used tires for free :-) When I lower the truck I will put the 255/70 tires on. I plan on going a wee bit lower in the front compared to slonaker's truck so hopefully they won't rub, I really don't want to go with a 60 series tire.

[Slonaker]

Originally Posted by 1986swb

Slonaker's pics detailed both the height and width of the tires as they sat in the fender wells at stock ride height.

I'm glad you found it helpful.

Originally Posted by chevymotocross

When I lower the truck I will put the 255/70 tires on. I plan on going a wee bit lower in the front compared to slonaker's truck so hopefully they won't rub, I really don't want to go with a 60 series tire.

IIRC, a couple of people have told me on this board that a 4" front drop will still clear the 255/70/15 tires. I want to go another inch, to 3.5.

Slonaker

[1986swb]

Now that I've decided on sizing: 255/70/15, I'd like your thoughts on tire brands that would work well in wet/dry weather and look good (blackwalls). Here are the tire brand options that I have found. I've read alot of threads from customers -- good and bad -- but I'd like your thoughts on them.

BF Goodrich Radial T/A
Firestone Firehawk Indy 500
Kumho Road Venture ST
Goodyear Eagle GT2
Kelly Charger

[1986swb]

BTW - Tirerack.com has a great selection of tires and honest/unbiased reviews from customers. Check it out.

[84 400]

they say fire hawks are not approved for light trucks... at least that is what the firestone dealer told me on our tahoe. they are real nice tho we got a set on our other car.

[Slonaker]

I'm on my second set of Radial TAs. They are overpriced, IMHO, but they are okay. When I was looking for tires, I noticed that the 255 Radial TAs were as wide as some other brand's 275s. Cheaper tires, like cheaper shirts, seem to be a little on the small side.

My favorite inexpensive tire was the General XP 2000. I like it better than the Raidal TA. I don't know if they are available any more.

Slonaker

[1986swb]

Interesting that the Firestone dealer told you that the Firehawk's were not for light trucks. Here's the Firestone marketing copy for the Firehawk tire:

"Firestone’s participation in the Indianapolis 500 Mile Race represents one of the longest relationships in motor sports. When you combine all of the Indy 500 victories earned by Firestone at the Greatest Spectacle in Racing, you have rich tradition backed by a history of performance. The Firehawk INDY 500 is a Performance All-Season tire that was developed for the drivers of cars and light trucks that want to celebrate that tradition by combining Firehawk performance tires with the INDY 500 and “Wings and Wheel” logo of the Indianapolis Motor Speedway."

Are you sure he did not want to upsell you on his other brand -- Bridgestone?

[84 400]

Originally Posted by 1986swb

Interesting that the Firestone dealer told you that the Firehawk's were not for light trucks. Here's the Firestone marketing copy for the Firehawk tire:

"Firestone’s participation in the Indianapolis 500 Mile Race represents one of the longest relationships in motor sports. When you combine all of the Indy 500 victories earned by Firestone at the Greatest Spectacle in Racing, you have rich tradition backed by a history of performance. The Firehawk INDY 500 is a Performance All-Season tire that was developed for the drivers of cars and light trucks that want to celebrate that tradition by combining Firehawk performance tires with the INDY 500 and “Wings and Wheel” logo of the Indianapolis Motor Speedway."

Are you sure he did not want to upsell you on his other brand -- Bridgestone?

Yeah. First off the tires look real good on there. Form my next set I am going with fire hawks on front and Hoosier or Mt on the rear. I think they said something about the load rating on the Tahoe and we do tow with it. I still think they fed us some bs but we have Firestone destination LE's on it now and they are a nice tire. We got 90,000+ miles on the factory original Firestone Wilderness Le's before the right rear tire broke a belt. It kind of stunk because they still had some nice tread left.

[1986swb]

Originally Posted by 84 400

Yeah. First off the tires look real good on there. Form my next set I am going with fire hawks on front and Hoosier or Mt on the rear. I think they said something about the load rating on the Tahoe and we do tow with it. I still think they fed us some bs but we have Firestone destination LE's on it now and they are a nice tire. We got 90,000+ miles on the factory original Firestone Wilderness Le's before the right rear tire broke a belt. It kind of stunk because they still had some nice tread left.

I'm sure load rating played a factor in the sales rep's recommendation to go with the LEs verses the Indy 500s. I haven't tried the LEs but I'm sure they perform well in both wet and dry weather, as they have many of the same tire attributes as the Indy 500s. I have noticed a HUGE difference in the way my truck handles and rides with the Indy 500s compared to those nasty light truck tires. Another benefit of the 500s is that they are quiet -- not as much road/tire noise when compared to the light truck tires. I researched many of the top name tires and I came to the conclusion that the Firestone Indy 500s were the best: warranty, thread life, wet/dry performance, and price.

[79GMC_OLDS]

i really like the look of those tires...would you be able to get a picture straight on from the front and/or rear just so i can see how wide the tires look?
thanks

[daveM]

Originally Posted by 1986swb

I have noticed a HUGE difference in the way my truck handles and rides with the Indy 500s compared to those nasty light truck tires. Another benefit of the 500s is that they are quiet --

Thinking hard about getting four of these tires. How are they holding out?

[1986swb]

Here are pics my new 255/70/15 Firestone Firehawk Indy 500 tires mounted on stock 15" x 8" steel rally rims. The truck is basically stock: 305H engine, 700 R4 transmission, rear end, ride height, exterior paint (steel gray) and interior. As you can see, the tires fit perfectly (thanks Slonaker for the advice and recommendations) and if I wanted to lower the truck, no problem. Additionally, if you want to check proper tire sizing, I found the following Web site on Tirerack.com extremely helpful. You can do a comparison with your stock tires versus various sizing -- tire diameter, tire height, speedometer readings and more. Check it out at http://www.discounttire.com/dtcs/infoTireMath.dos

What do you guys think?

[1986swb]

Here are two additional tire pics to show you the spacing relationship between the tires and the truck fenders:

[Albatrossian]

I'm running Uniroyal Tiger Paw GTS's, 255/70s and they look good and ride very well with no road noise on mine.. I am going to 275s on it though, as I don't plan any lowering other than dropping the back end to level it out. I just like the look of a fat tire on it!

[daveM]

Thanks 1986swb. I'm going to get them tomorrow I think. The 255s as you say they are 29.1 high.

Albatrossian... the 275s are wide eh? I looked at them but I wanted to fill the hole a bit more. I think the 275s are around 28" high. My '87 came from the factory with 225s and I think they are 28.3 so speedo shouldn't be too bad in either case but I'm getting the 255s.

[1986swb]

Originally Posted by daveM

Thanks 1986swb. I'm going to get them tomorrow I think. The 255s as you say they are 29.1 high.

Albatrossian... the 275s are wide eh? I looked at them but I wanted to fill the hole a bit more. I think the 275s are around 28" high. My '87 came from the factory with 225s and I think they are 28.3 so speedo shouldn't be too bad in either case but I'm getting the 255s.

I like the 255s as I can rotate the tires. Going larger in the rear, you can go as large as 295 but be prepared to purchase front tires sooner than later. Remember, if you go large tires all around (i.e. 275s or larger) they may put more strain on your front end and steering components. Something to consider.