Hey Guys,
Our truck looks great but still needs some TLC to actually drive great.
We've got a 1950 F1 with a 351W/AOD as a drivetrain & a No Limit Coilover IFS up front with an Explorer rear end. The truck has 2,000 miles on it since returning to life.

The existing Tires/Wheels on there are 255-45-ZR18's Dunlop Direzza's.
They fit fine out back with 2 inch spacers - but up front they are just too big! Alignment places can't do anything as the tires sit too close to the fenders. The front tires are splayed out in front - looks like the truck went over a jump .... So how do I get out of this predicament?

o Same style wheels are $250 ea plus tires @ $150 - $800 to replace the front wheels/tires with 17's? 16's? That's pretty pricey ..

o Can I run 16's on the front & 18's on the back?

o Get some more period correct looking wheels?

o Can I put "smaller" skinnier tires on the same wheels? What offset do I look for?

Just looking for general wheel/tire advice? What would you do? (My 20 year old Zack picked this style wheel - I'm not sure I want to keep buying more of them...).

Ben in Austin

 

1. Yes, you can run different rim sizes front to back, you just get different sidewall height depending on tire size and profile.

2.Smaller/skinnier tires on the same wheels - depends on what the rim size is and what you are running now. You can check tire sites for compatibility .
I like this one: Tire Size Calculator - tire & wheel plus sizing


Not quite sure what you mean by the tires being splayed out. If they are further out on the bottom than the top, it sounds like you need heavier springs to straighten it out (not an IFS person, but is the bottom control arm parallel to the ground?). That would give you more clearance as it would push the suspension down.

Good luck - you have a great looking truck.

 

Hey Dmack,
Thanks - If I stay with 18's in the back would 16's work up front?
Can you do that much difference in tire size?

THe current look straight on is the top of the front tires are tucked in under the fenders & the bottom splays out noticeably wider. I'll check to see if the A arms are parallel with the ground.

Ben in Austin

 

The thing you have to remember is that the rim size has a small effect on the actual tire height.

For example, your current tire size is almost identical to what I am running on the back of my truck, which are 255/60R15.

The width is the same between the two (that is the first number - 255 which is the section width in mm). From there, mine have a higher sidewall to width ratio (aspect ratio, 60 vs. 45) and a smaller rim (15 vs. your 18"). But overall, they are the same height and width. Yours just have a taller rim and correspondingly shorter sidewall which cancel each other out.

How wide are your rims?

Just playing with tire rack and the link I posted earlier, you could keep your 18" rims and run 225/40/18 tires, which would be 2" shorter and 1.25" narrower than what you are currently running, and they will fit on 7.5-9" wide rims.

By playing with the section width and aspect ratio, you can juggle tire heights and widths. If you could use your current rims, which look great BTW, you could save some $$ too. Just remember, as you reduce the aspect ratio, the sidewall gets shorter, so you have to be careful not to bend a rim on things like potholes, speedbumps, etc.

 

Thanks again Dmack,
I'm just retarded when it comes to this tire size stuff - I tried the calculator but I wasn't sure what to make of it. So you think I can possibly just change out the tires but not necessarily the rims - that would be nice.

Ben in Austin

 

You can, the main thing to deal with is how wide your current rims are, as that will be the limiting factor in keeping them.

Checking further, you could go to 215/45/18 (7-8" rim) will be 1.5" shorter and narrower than you currently run, and 215/40/18 (7-8.5" rim) would be 2.25" shorter and 1.5" narrower.

You can visualize the difference in tire height by thinking of it as taking 1/2 the height difference off the top, thereby adding clearance. So if you went with a tire that was 2.25" shorter overall than you are currently running, it would give you 1 1/8" extra clearance between the top of the tire and the bottom of the fender.

If you have a good tire store, they could walk you through the process. I would also talk to the alignment shop and ask them how much more clearance they would need to be able to align the front end.

Back to your original statement about it looking like it had gone over a jump, if the tires are kicked out further at the bottom than the top, it sounds like a spring (or coil-over shock, if that is what you are running) issue. If you could dial that so that they were flat, it should be giving you extra clearance at the top of the tire also.

There are a lot of more knowledgeable people out there on this topic, so hopefully they will chime in.

 

Dave is right, you can stay with your current wheels and get a narrower and shorter tire. That would give you some room around the fender, which would allow some room for the alignment adjustment. Personally, I like the big/little look (taller rear/shorter front tires) but it isn't for everybody. I think a 16 inch wheel would look good on the front and would allow you to run a shorter/narrower tire without going to a 40 series. A 40 series (sidewall height) would have no sidewall flex, which would give a harsher ride and be more prone to damage from potholes, curbs, and such.

You also mentioned going to a period correct wheel style. As you know, you can do anything your wallet allows. You could always see if someone wants to buy your tires/wheels. Assuming you have the smaller bolt pattern with the Exploder rear end, those wheels will fit lots of different vehicles.

I also agree with Dave, your truck looks amazing.

Oh, and you're making me nervous with that engine stand so close to the truck. Your truck really deserves a stall all to itself.

 

Thanks Jeff,
Our's is one of those builds where the truck look has really worked well but the mechanical & ride need some time to catch up. I'm in the prolonged "shake down" phase -
o Get the ride right up front - I need to fix this splayed out look with
a normal looking tire/wheel set up. 18 inch wheels don't leave us
much room for sidewall flex.

o Get the AOD shift points up so it doesn't bog down when driving around
town under 40 MPH.

o Need to double check the vaccum set up & timing on the 351W as I'm
really not sure it's set up right - Siginificant hesitation (but it could be
related to the AOD as well).

o Fuel Gauge - 1970 Mustang tank out back - float not working right - registers half what it should...

I'm not sure you ever are totally "done" - lot's of cosmetic interior
things to consider. Our paint "job" is nowhere near show quality - but I don't need much to knock around town - this is a weekend truck that will be used.

Thanks for you help - let me think through the wheel/tire dilemma & see... I'm going to circle back on the 351W tuning advice as soon as I knock this one out.

Ben in Austin

 

Ben,

On the fuel gauge, I think the newer gauges use a different resistance level (don't quote me, but I was thinking 90 vs. 45 ohms). That would give you the wrong reading on the gauge. I don't know if you can run a resistor inline with it to change it or not though.

I agree with Jeff in that I am not a big fan of the low sidewall height on tires these days (60s were as low as I was willing to go). I was just trying to give you an option that would cost substantially less than changing both the tires and wheels. I know you have put a lot of $$ in your truck, and the quality shows. Sometimes it is nice to make do with some of what you already have and save the cash for other projects.

Keep up the good work.

 

I like to use this to see the difference in tire sizes. This may help you to see how the wheel/tire combo effect the overall diameter, width etc.

Tire Size Calculator - tire & wheel plus sizing

 

Tire tucked in more at top than bottom means your camber is messed up. You have too much negative camber. Your tires should be showing wear on inside more than outside. If you get the alignment fixed (camber, caster and toe), then you can figure out where your tires should sit. My recommendation is inside the lip, not flush with outer lip.

I would run smaller 16 or 17 inch front wheels with less width or offset, and skinnier tires. More of the big and little appearance. You may need to adjust the front height, make sure the tire sidewalls are proportional. Your truck is not one that will have any problems with the different sizes. It does not have ABS or traction control that new trucks have where different sizes can mess these systems operation up.

 

Hey 38COE,
I tried to get the alignment done again to straighten things out so
I could see what makes sense but the shop said they couldn't do anything until I got wheels/tires that would fit under there better. (I've had alignments at 3 places).

Seems as though the passenger side splays out more than the other side.
I could go with thinner tires & see if that gives me enough room. Is there any "home alignment" process I can use to get it about right?

Ben in Austin

 

Yes, you can do it reasonably well at home: a level, tape measure and an angle gage can do wonders. Search aorund here on on the net for do it yourself alignment.

 

Ben, I know the pain of buying a whole new set of wheels and tires. As you know it happened to me. My fronts are now 205/65R16 which are a little over 25" in diameter. The rear are taller and wider 235/75R16 which are 29.5 in diameter. I like the looks of it and they work. I was thinking about getting F2 front fenders for a while, but don't need to now.

 

I'm also playing with the rim / tire thing; have MII IFS with Explroer rear.

I had Ford 15" rims (4.5" backspace) on my "roller" but didn't have the clearance on rear tires so I went with late 80's 15" rims (3.75) and am shopping for tires (185 70R 15) which are about 26" diameter.M y front Is lower than I would like with 8.5" clearance on front bumper. Tried taller springs but didn't raise front height; will try later. Right now 'm concentrating on getting registration.