Searched Archives...not finding what I need: Tire fitment

[KevinsOffroad.com]

First, hello to all. I've been gobbling up all sorts of great information from the forum for the last few days. I answered an ad on Craigslist for a local Arizona guy named Eric (AzRatRod here on the forum) who told me about you guys during our conversation. I'm really happy he did, too!

I'm going to post up a pic of my grade-C condition '66 Shorty, which I'm tinkering with as my newest project so you guys can get an idea of what I'm working with.



First, does it appear to you that the truck has been lowered at all to your eyes, or are we just seeing the effect of saggy springs? I'm currently running 15" wheels and 245/60r15 tires, to give you a perspective. The rear has 5 leaves in the leaf pack, not including the upper "helper" spring. Seems like I have about 4" of uptravel from the bumpstop to the axle tube back there. In the front, I can't tell if I have factory coils, or modified, or what. I seem to have about 2" of uptravel from the bumpstop to the I-beam arm.

Second, I'm curious if you can tell me, knowing what you now know about the height (which I'll lower a bit if I move the ride height at all), what the tallest and widest tire I can fit without rubbing. I was going to use wheel adapters and bolt on some 18" wheels I have already, along with some 235/45r18 used tires that I own (about 26.5" tall), however, I'm also able to get a smoking deal on a set of wheels and tires in 20" size (brand new).

I don't want to have rubbing issues, so I thought I'd ask the experts who have done a slick up with tall wheels and lowered it what I should be looking for size-wise. Eventually I'll be doing a Lincoln/Crown Vic style front end, however, I'm not going to spend the time to do it until a year or so out.

Thanks,
Kevin
KevinsOffroad.com (we build Jeep parts for a living)

[36truck]

from Michigan. Some of the guys that have lowered truck can tell you what works. You can fit a good sized tire under these trucks. Good looking truck.

[Anthony]

Welcome from West Virginia.... I don't know too much about the tire fitment but it doesn't look to me like your truck has any lowering done to it. It looks right to me. the eye will play tricks with the wheel to fender opening seeing how the rear is not cut as high as the front. just my opinion. Glad your here, just stick around, someone here knows these things...

[f100jim]

Welcome to the forum. Your truck height looks stock to me. This is a good place for info. jim

[ronk16]

i got a 29.5x15.5x 16 on the rear of my 66 step, with a 12inch wide wheel and 5.5 back space, basically pro street tires out back and 265 75 15 up front. and a crap load of room to spare. stuffing some 20`s should not be a problem.

[blackagatha]

AWW NAAW!

you're gonna roll her on 20's? lol....

keep that schit on the escalators. hee



but nice truck...

Go for FAT Rubber, not tall rims! hahah

[KevinsOffroad.com]

So far, it seems the consensus is that there is not much, if any, "drop" done to the suspension, so at least I know where I stand with that. Thank you guys!

So, with respect to changing out a rear tire if I were to get a flat, is there a tire width that will impede my progress on the side of the freeway? If the truck was any lower, or the tire was too wide, will I get to a point where I'm unable to get the flat tire out of the wheel well because it's too wide?

Thanks, and my apologies for all the silly questions...I just don't want to get the wrong size tires and wheels.

Kevin

[64 f100]

The general consensus is that a about all you can get under ther rear is about an 8 inch rim. I have run wider but it is really to close, but I don't know how much more offset you can run to get wider. Not much I think. As to what will fit in taller rims, sorry I can't say. I know younger people like tall but I'm just not into it , especially as tall as 20's. the trucks don't really lend to that design, but my opnion so? Fronts, 7 inch rims will work well, get any wider and then you will have rubbing issues with frame etc., without offset. One thing you should know about these trucks before you go with wheels. The front end is wider thatn the rearend. This happened when Ford went to twin I beam . This pushed the front wheels farther out. If you ever folled a Ford truck down the road, it often looks like it is side tracking. This is caused by an illusion becuase the rearen tiers are farther in than the front. A wider rim in the rear helps the truck look better from that standpoint. Other considerations, and this is the killer one. To drop these trucks means front end geometry is tricky and expensive to fix. Drop axles are available and cost is high along with other parts that need to go with the alteration. My advice reagardles is new front springs and shocks if going this way. Rearend islimited by other geaometry as mentioned by you. You could remove or modify the bumpers and get drop hangers to do the job. Personally, I've always thought the rearend on our trucks have sat to high. May be because the frontends have sagged over the years and need new springs or it may have been designed that way.

Rich

[Gary Seymour]

My '62 had 7" form the axle to the bumpstop originally, in the rear. And it also seems like 2" on your front end to the bompstop is not much travel either.

From your picture, it doesn't appear to be much lower than stock. But it sure seems to me that stock suspension travel would be more than 4" rear and 2" front, especially without a load in the truck.

That looks like a very nice body on that shorty! Great one to work on.

[Uncle Skip]

Welcome from sunny Houston, Texas (at least for now).
I'd say your truck is sitting at stock height too.
You can get lowered beams for that old fashioned California rake but if you're going to slam it all around, well, ???????
And I would think that if you dropped it very much in the front you'd have some problems with large rims because the 65-66 trucks are afflicted with polio. They are wider in front than in the rear, the tires stick out further and they WILL rub (not to mention that they look funny going down the road from behind).
BroncoTom put the 16" Gen 1 Lightning wheels on his truck with good success. But he'd have to tell you the tire sizes.
I have 8" rims with 2.75-70/15's on the rear of my truck and I have good clearance and 7" rims with 2.25-75/15's in the front, but my truck is a straight axle '63.
My personal opinion (for what little it's worth) is the bigger rims don't function well on the trucks because of the sidewall clearance. And I don't like anything with no sidewall regardless of what its on. I leave that stuff to the low riders and ricers.
Anyway, its your truck so do it your way ----- except puting an Government Motors engine in it. LOL
And we're sure glad to have you here.
Uncle Skip aka U@ss

[effienut2]

Greetings. Like you I have found this to be a great website.

I have '66 lb under which I can only have 75 series tires. I think they are 275x 15. I also have a '66 sb under which I was able to fit 60 series tires. The difference is that the lb has a wider rear axle than the sb, about 4 ". This is because the lb has an axle from a later model F100 (150?).

On the sb I have 245 x 15 in the front and 260 x 15 in the rear. I also removed the 2 shortest leafs from the spring pack, including the real thick one. The ride is terrific. The truck sits about 2" lower than the lb. Also I installed a disc brake front end on both trucks using the complete front end from a 73 - 76 F100. One thing that stood out on one of the conversions I did was that it had a weak coil spring on one side so I purchased a new set. Interesting that a note came with the new springs that specified which side each coil went on.

Good luck on your truck.

[TxSlick66]

235x45/18 will be way too short. A 235x50 would even be pretty short in back. My truck (for now) has 15x8 wheel with 3.75" backspacing and 275x60/15 on the rear and it looks right at home in there. About 3/4" clearance outside between the quarter panel.

Your truck does not look lowered to me. Mine sits where the rear fender lip is about even with the top of the wheel (not the tire, but top of the wheel). It has a couple of spring leafs removed.

[BlueGhost]

As far as I know my truck is stock height, it might sit a little lower due to the age of the springs. I'm running 235/70/15s in front on 7 inch rims and 275/60/15s in the rear on 8 inch rims.

[albumimg]6084[/albumimg] [albumimg]6083[/albumimg]

This gave me 28 inch tall tires front and rear. That's about 9 inches of thread and an 11 inch cross section for the tires on the rear. And 7 inches of thread and a 9.5 inch cross section on the front. The rear wheels have 3.3 inches of backspacing and the fronts have 4 inches of backspacing. I think if you were careful with the backspacing you could fit a 10 inch rim on the rear.

[jkimbrel65]

I have 10 rims with 285/70/15s on the rear.Backspacing is 5 1/2 have 3/4 clearance both inside and out.Tire is 31 1/2 tall