I am new to this forum. I have been doing extensive reading trying to determine the proper size and backspacing to go with on my older truck. I have a pretty good idea of how all these numbers work but most of the posts I have read on here are from several years ago. Also, the actual answers in the posts weren't directly relevant. I am in need of new tires so I figure to go ahead and buy some aftermarket wheels while I am at it.

I have a early 1999 F250 7.3L. Because it is an early, it has the 4inch blocks in the back but otherwise stock height. I have contemplated leveling the front. I want to step up from 16" stock wheels to 18" wheels.

Based on what I have read here and math from here (Custom rims, wheel tire packages for your ride - RIMSnTIRES.com)....

1) 18X9 -12mm offset rim with a LT305/65R18.
Will it work? Will it rub without lift/level kit? How far past the fenders will it stick out?

2) A less aggressive choice 18x9 0mm offset LT275/70R18.
Will it work? Will it rub without lift/level kit? Would a -12mm offset wheel still be preferred to maintain the 4.5inch backspacing.

On the tire and wheel calculator, I have been basing all my measurements on LT265/75R16 16x7 6mm Offset. Thanks for anyone who responds.

 

Anyone have any insights?

 

Give people time to wake up today and get home from work, you will no doubt get a answer soon. Wish I could help you but good luck!

 

I will say that without a level kit you may be able to run 285's but not sure on the 305's. Someone here I'm sure has the same truck and build and will be able to chime in with accurate information soon. Maybe take a ride to your local tire shop and have them test fit to see, not drive with them but perhaps they will test it on and allow you to turn steering to max to verify fitment.


Also, they may be able to answer you question much faster if you don't a response later today on here.

 

Sorry guys I get a little excited. Lol I'm an early riser and a late setter. There's no good local tire shops out this way, maybe an hour or more away in the city I'd guess.

 

Someone will take car of you I'm sure but maybe call the shop then and just ask if you don't feel confident at least you can compare to what experts here will say.

Who you going to have install the tires once you get them? I would try that shop at least you know once you talk to them you can be sure they know what they are talking about.

 

Yea, I can install and mount them. In a weird turn of events - Im a tech at a Ford dealer in a small town. We only have 3 techs and mostly family run and opperated but no one knows for sure here.

 

Man it really looks like, based on the math, that the 305 will not hit the leaf springs, but I am more worried that it will hit the fender/bumper. Also, it appears that the 275 on a 0mm offset wheel will allow the tire to be exactly at the same distance from the suspension as the stock wheel so it shouldnt hit either. Was really hoping someone had a similar setup.

Iv read in several instances that a 285/65R16 will fit on stock rims no rubbing, which would put the tire 0.4 inch closer to the suspension components and stick out 0.4 inches further with a total height of 32.8 inch so in comparison that 305 mounted on a 18x9 with -12mm offset would allow more space between leaf springs and stick out an additional inch. Ahh, so confusing.

 

I run 315's on my truck, but I have a leveling kit on it.

I dont have any good pictures of the front wheel wells with tires.

I am interested to know what rim you go with, as the PO but rims that allow the wheel to rub at full tilt (the PO put the tires and wheels on before I purchased the truck).

 

I thought about just ordering from discount tire direct - rims and tires installed shipped to my house sounds enticing. I am glad to hear you can run the 315's with a leveling kit. Whats the rest of the tire size for comparison?

We got a truck in at the shop now that has 315/60r18 (33x12.5). Seems like they stick out too far. The owner has fender flares to help the look. Im not interested and using the flares.

Im really leaning toward a leveling kit anyway since the truck sits with a 4inch rake, I just didn't want to push my size too large. I never wanted to because I only have 1/2inch clearance from the top of the my home garage door to my running lights - but that is going to be gone regardless bigger tires lol.

 

Not a great pic but these are 35s on 20×10s on my 2003, stock suspension, minimal trimming to inner fender well.