Wheel and tire sizes offset/backspacing

[Whacka]

I have tried the search function for an hour or so and I'm possibly just impatient or stupid but hopefully yall can humor me. all the threads I've searched are old or don't have the information I'm looking for with pictures etc.....

I have a 1998 explorer awd 5.0 and I'm looking for a summer wheel set up with the widest possible with no rubbing as I enjoy grip and I plan on lowering it as much as I can which seems to be 2 inches? sad... if anyone has info otherwise on that as well i would be excited to hear it! PS don't want rubber bands but not looking for big sidewall either lol

 

[CDW6212R]

Try a 255/60/17 at 25mm offset(max), or a 275/55/17, or an equivalent size in the 29-30" diameters. I had that first size on my Mercury for 35k miles, and that 2nd size I have right now mounted on 17x9's(16mm offset), yet to fully test fit.

A 275/55/18 for example is 30" tall and will fit with the right offset around 15-20mm on a 9" wheel. That 275mm wide tire will require an offset to move them out enough to clear, use the 15-20mm range as a starting guide.

But, in any case, the rear parking brake cable is partly in the way of a wide tire in the rear. You will have to tie the cable inboard a good bit to clear wider tires. On the 302's those have an extra suspension link going from the rear to the frame, you can R&R the parking brake cable and route it inboard of that bar.

Lateral movement of the rear in cornering will limit wide tire sizes in the back, stiffening up the lateral movement is ideal. Replace the fifth shock with a very heavy duty version, a worn out shock there will allow more tire rubbing. I used a Bilstein set of five, that helped some in the back. Any worn out bushings will allow things to move around more, and cause more tire rubbing. So tighten up the suspension parts if you push the tire sizes a lot.

 

[Whacka]

Try a 255/60/17 at 25mm offset(max), or a 275/55/17, or an equivalent size in the 29-30" diameters. I had that first size on my Mercury for 35k miles, and that 2nd size I have right now mounted on 17x9's(16mm offset), yet to fully test fit.

A 275/55/18 for example is 30" tall and will fit with the right offset around 15-20mm on a 9" wheel. That 275mm wide tire will require an offset to move them out enough to clear, use the 15-20mm range as a starting guide.

But, in any case, the rear parking brake cable is partly in the way of a wide tire in the rear. You will have to tie the cable inboard a good bit to clear wider tires. On the 302's those have an extra suspension link going from the rear to the frame, you can R&R the parking brake cable and route it inboard of that bar.

Lateral movement of the rear in cornering will limit wide tire sizes in the back, stiffening up the lateral movement is ideal. Replace the fifth shock with a very heavy duty version, a worn out shock there will allow more tire rubbing. I used a Bilstein set of five, that helped some in the back. Any worn out bushings will allow things to move around more, and cause more tire rubbing. So tighten up the suspension parts if you push the tire sizes a lot.

How's the fender to wheel fitment? Thank you for all the info too btw!

 

[CDW6212R]

A 30"+ tire on a lowered 2nd gen Explorer is going to rub the plastic inner fenders barely at the center. The diameter and the truck lowered makes that a rub point to watch for. My 265/60/18's did that the most, that's a 30.5" tire.

You cannot lower these trucks a lot really in front due to the alignment problem, and worsening ride quality. I had great success lowering my 98 Mountaineer, but my other three 2nd gen's would not let me lower them very much at all. The Camber gets bad as the truck gets more than about an inch lowered, it varies with every truck. My Mercury could go about 3" down I think with no huge alignment issue, I played with the height for a couple of days before choosing where I liked it and left it, a little over 2" I think.

I measured my trucks from the LCA front bolt center, to the ground. My Mercury is about 2" lower than my other three trucks, each of them at the alignment shop they told me the camber was bad at lower heights. I typically went there each time with the height where I wanted it. hey would tell me how bad the camber was, and we'd settle on a height above that where they said the tires would live. Note I like hard driving, cornering, so a little negative camber is good for me, and my alignment shops knows this. So other people could have to have less camber than me, because they'd wear out the inner edges fast. I even that out by wearing out the outer edge in driving style.

I used the proper camber washer kits with bolts in all of my trucks, for some reason my Mercury was great and the others aren't. My black 98 Limited will be my keeper, so I will have to figure out how to make that go down more.

That being said, the tire width will be limited slightly by how far the truck is lowered, but the wheel offset the most, and what kind of fender flare you have. I'm going to add the optional front flares that are the slimmest, came on many base models, and is about 1.5" wide. The 17x9" wheels I will use are 16mm offset, and with no spacer they will set the tire out of the fender just a bit, about an inch. The limit on the inside is the upper BJ, you have to keep the tire away from those by a good amount, say 1/2" depending on the wheel diameter and tire series. Shorter wheels and taller tires need more clearance for the tires to deflect.

This is the only picture I find handy to show the first tires I put on my Mercury. These are 255/60/17's, with a 1/4" spacer(30mm offset 17x8" wheels(which makes them about 24mm offset(1/4" is 6.35mm))). I had the truck lowered then with the Explorer Express kit, 2 38" rear lowering blocks and front bump stops from a Limited. I lowered it slightly more when I wore those tires out, but it's still very close to that. If you go much lower or bigger with tires etc, you get closer to rubbing. I had none with those first tires, but went to a 265/60/18 next, and worked my way down from there. Now it has 255/55/18's which are 29" tall like the stock 15's and the 17's were.

I would suggest the size range near a 275/55/18 as a limit(that's a 30" tire) with less lowering than with a 29" tire. I was hunting a wheel that was either 17x9" or 18x9", and found two of the 17's first. I was after a particular wheel, so there are lots to choose from, the offset is the big key when you push the tire sizes and lowering.

 

[Whacka]

A 30"+ tire on a lowered 2nd gen Explorer is going to rub the plastic inner fenders barely at the center. The diameter and the truck lowered makes that a rub point to watch for. My 265/60/18's did that the most, that's a 30.5" tire.

You cannot lower these trucks a lot really in front due to the alignment problem, and worsening ride quality. I had great success lowering my 98 Mountaineer, but my other three 2nd gen's would not let me lower them very much at all. The Camber gets bad as the truck gets more than about an inch lowered, it varies with every truck. My Mercury could go about 3" down I think with no huge alignment issue, I played with the height for a couple of days before choosing where I liked it and left it, a little over 2" I think.

I measured my trucks from the LCA front bolt center, to the ground. My Mercury is about 2" lower than my other three trucks, each of them at the alignment shop they told me the camber was bad at lower heights. I typically went there each time with the height where I wanted it. hey would tell me how bad the camber was, and we'd settle on a height above that where they said the tires would live. Note I like hard driving, cornering, so a little negative camber is good for me, and my alignment shops knows this. So other people could have to have less camber than me, because they'd wear out the inner edges fast. I even that out by wearing out the outer edge in driving style.

I used the proper camber washer kits with bolts in all of my trucks, for some reason my Mercury was great and the others aren't. My black 98 Limited will be my keeper, so I will have to figure out how to make that go down more.

That being said, the tire width will be limited slightly by how far the truck is lowered, but the wheel offset the most, and what kind of fender flare you have. I'm going to add the optional front flares that are the slimmest, came on many base models, and is about 1.5" wide. The 17x9" wheels I will use are 16mm offset, and with no spacer they will set the tire out of the fender just a bit, about an inch. The limit on the inside is the upper BJ, you have to keep the tire away from those by a good amount, say 1/2" depending on the wheel diameter and tire series. Shorter wheels and taller tires need more clearance for the tires to deflect.

This is the only picture I find handy to show the first tires I put on my Mercury. These are 255/60/17's, with a 1/4" spacer(30mm offset 17x8" wheels(which makes them about 24mm offset(1/4" is 6.35mm))). I had the truck lowered then with the Explorer Express kit, 2 38" rear lowering blocks and front bump stops from a Limited. I lowered it slightly more when I wore those tires out, but it's still very close to that. If you go much lower or bigger with tires etc, you get closer to rubbing. I had none with those first tires, but went to a 265/60/18 next, and worked my way down from there. Now it has 255/55/18's which are 29" tall like the stock 15's and the 17's were.

I would suggest the size range near a 275/55/18 as a limit(that's a 30" tire) with less lowering than with a 29" tire. I was hunting a wheel that was either 17x9" or 18x9", and found two of the 17's first. I was after a particular wheel, so there are lots to choose from, the offset is the big key when you push the tire sizes and lowering.

View attachment 325323

I'm considering 18x9.5 inch or 19x9.5 inch and the offset choices are +15, +22 or +35 wheels with more a lower profile tire such as 275/40 maybe a 275/45 I THINK from what you're saying +22 will work with no rub and no be outside the fender although is there anything inside that i need to consider it may hit? more of a street machine and ride quality isn't a HUGE concern. In the future I plan on fabbing tubular control arms to allow for a coil over suspension set up but as of now it's going to keep the torsion bar. This may be a bit much to ask but do you have any links for camber kits I can buy to have on hand when I'm ready for an alignment? 2 inch lowering blocks and taking out the key bolts seems to be the easy standard thing thatll work. I wish we could have an in person conversation lol you seem to be a wealth of knowledge and I'm loving it

 

[CDW6212R]

The 22mm offset would be on the edge with 275mm tires, that's the part you'll have to decide on for inside clearance. The BJ is the major item in front, and in the back it's the parking brake cable, and then the inner fender above the frame rail. That inner sheet metal hasn't been an issue but most people don't go near a 275mm tire there. That area is vertical and can be pushed inward a bit(it's not attached at the bottom).

The 45 series tire for a 18 or 19" wheel makes those a 28" or 29" tire. If those are the kind you prefer, try to lean to the 19" size and 40 series, that would be around 29", a good size diameter for these trucks.

There are already tubular UCA's, about $650 from BTF; Ford ranger uniball upper control arms-coil spring truck

There are also coil over brackets you can buy to weld to the frame and LCA's, to mount coil over springs/shocks.

There are lowering keys(drop keys), you should buy those first before an alignment. They run maybe $40 on eBay if they are still easy to find there. They let you keep the adjustment bolts to fine tune the height.

To go 2" or more in back, the leaf springs need to be stiffer than the softest which came on Mountaineers and the Explorers with air shocks. My Mercury(rear) bottoms out on hard dips or with any small load in the back. I think you have the ARC suspension on your 98 EB, it was standard from 95-98. Check the rear cargo jack area, above and behind the jack. In the corner near the top will be a switch for the ARC, to turn it on and off. If you have that ARC, then the springs are the softest Ford put into these. I swapped my front torsion bars when I rebuilt the front suspension, that helped handling and the possibility of bottoming out in front. It hardly did before, and it helped even more.

The camber kits are almost easy to find by searching for "camber washers" on Rock Auto or Amazon, ebay etc. They run about $15 a side, you buy two kits, and there are several brands that are virtually identical parts. So choose the parts that seem to be the best brand or quality, skip the versions that mention lesser adjustment camber amounts, you need the most degree gained. If you don't like the suspension or mechaincal work, let the alignment shop install them. They are a pain on the left side the first time you do them, and not fun after you know how they go in.

 

[Whacka]

The 22mm offset would be on the edge with 275mm tires, that's the part you'll have to decide on for inside clearance. The BJ is the major item in front, and in the back it's the parking brake cable, and then the inner fender above the frame rail. That inner sheet metal hasn't been an issue but most people don't go near a 275mm tire there. That area is vertical and can be pushed inward a bit(it's not attached at the bottom).

The 45 series tire for a 18 or 19" wheel makes those a 28" or 29" tire. If those are the kind you prefer, try to lean to the 19" size and 40 series, that would be around 29", a good size diameter for these trucks.

There are already tubular UCA's, about $650 from BTF; Ford ranger uniball upper control arms-coil spring truck

There are also coil over brackets you can buy to weld to the frame and LCA's, to mount coil over springs/shocks.

There are lowering keys(drop keys), you should buy those first before an alignment. They run maybe $40 on eBay if they are still easy to find there. They let you keep the adjustment bolts to fine tune the height.

To go 2" or more in back, the leaf springs need to be stiffer than the softest which came on Mountaineers and the Explorers with air shocks. My Mercury(rear) bottoms out on hard dips or with any small load in the back. I think you have the ARC suspension on your 98 EB, it was standard from 95-98. Check the rear cargo jack area, above and behind the jack. In the corner near the top will be a switch for the ARC, to turn it on and off. If you have that ARC, then the springs are the softest Ford put into these. I swapped my front torsion bars when I rebuilt the front suspension, that helped handling and the possibility of bottoming out in front. It hardly did before, and it helped even more.

The camber kits are almost easy to find by searching for "camber washers" on Rock Auto or Amazon, ebay etc. They run about $15 a side, you buy two kits, and there are several brands that are virtually identical parts. So choose the parts that seem to be the best brand or quality, skip the versions that mention lesser adjustment camber amounts, you need the most degree gained. If you don't like the suspension or mechaincal work, let the alignment shop install them. They are a pain on the left side the first time you do them, and not fun after you know how they go in.

It's been a while since I have responded because I wanted to do enough research. I have the eddie bauer fender flares so I'm thinking of getting away with 19x9.5 +15 and running spacers if need be to push them out a bit since I do have the fender flares anyway so there shouldn't be any poke. I found QA1 weld in brackets for coil overs onto solid rear ends so leaf springs will go away then I looked up on the forums and found the front end coil overs you mentioned which ironically is for a lifted vehicle when I'm going to lower mine kinda made me chuckle. Those upper control arms will fix the alignment issues I may run into with camber so that was a huge help! Last thing I need to figure out is the coil over clearance near the axle when lowered. I'm ASSUMING since the guy off roads and more than likely tucks that tire up in the fender I won't have any issues but planning on messaging the guy this coming year when I start purchasing everything and start bringing the summer car back out so this one can be out of commission for a while. All in all what do you think? you seem very knowledgeable and need the banter/second opinion.

 

[CDW6212R]

I don't know anything about the rear end coil over spring possibilities, hadn't heard of that before.

The front coil over spring parts are made for lifted trucks, true. But some have done it without any significant lift at all. The spring height and strength is the major factor to set ride height, and it's adjustable in a certain range for each spring etc. So you might consult with a couple of members who have a lot of experience with different springs and heights.

The front coil over kits alter the upper shock mounting, some people cut off the old one completely to make more room for a bigger shock or lift. You might not need that, and I'll be going down that road when my truck is close to done. I plan to do that and paint, and engine, last.

Your OEM flares do give you quite a bit of added tire coverage, maybe near 1.5" on each flare. My rear tires will be a problem, and I hope I can get a friend who used to be great at old style rear flaring(steel), to alter my rear quarters a little to flare the edge a bit. I have a wider rear end in mind.

 

[Carson starr]

I have tried the search function for an hour or so and I'm possibly just impatient or stupid but hopefully yall can humor me. all the threads I've searched are old or don't have the information I'm looking for with pictures etc.....

I have a 1998 explorer awd 5.0 and I'm looking for a summer wheel set up with the widest possible with no rubbing as I enjoy grip and I plan on lowering it as much as I can which seems to be 2 inches? sad... if anyone has info otherwise on that as well i would be excited to hear it! PS don't want rubber bands but not looking for big sidewall either lol

305 z?

 

[Whacka]

305 z?

?