Hi, I was contimplateing getting slightly larger tires on my truck from what I have on there now. I have the stock Firestone Steeltex A/T tires on my truck, which is a 2001 F250 XLT regular cab 4x4. The tire size on the truck now is 265/75/R16. Which after looking on the firestone web site I found that the diameter of the tire is 31.7 inchs. I was wondering, I know there is more room in there for some larger tires, but what is the max size I could go without adversly affecting my gears and such? Would it be 33 inchs ? I was looking at 33x12.50x16.5 inch Super Swamper TSL's or TSL Radials. If these were to fit, what would be the best backspaceing to get on the wheels to insure that the tires fit right and dont rub. Thanks for your time. John.

 

I had the same questions as you and went with 285/75R16 Procomp A/Ts. They don't rub at all, didn't make much difference in gear ratio, but do fill in the wheelwell better than stock. Again, I don't see your sig; some engine applications make the fron sit lower than others. See my sig.

 

I just put a set of Big O 215xR75x16 A/T's on mine all around. The fronts rub very slightly if I turn hard (bottom out the wheel) while into a corner. The inside wall of the right tire just barely rubs the leafspring. I've been told that just an extra leaf shim up front would be enough to stop the problem.. My current lift is stock.

 

Typo in that last post. It should read 315!

 

The 33x12.50-16.5's you're considering are about the same diamter but a little wider than the 285/75-16's that are a popular swap size on these trucks. I have the 33x12.50's on my F350, though my truck is a little older ('92) and they fit fine on my stock 4x4 suspension with only a little forward shimming of the stock front bumper to keep them from rubbing while turning.

Whether or not the increased tire diameter makes a noticeable difference in power depends on what size engine you have and what the current gear ratio is. If the engine is small and the ratio is already on the high side (numerically low), then the increased tire size will have an adverse effect that you may notice as decreased power when going uphill or starting from a stop. If your engine is plenty powerful for your truck weight and your gear ratio is already low enough to allow for some playing around with tire sizes, then you should be ok with the 33" tires.

With a 12.50" wide tire, you will want to put them on wider wheels. Mine fit beautifully on 10" wheels. 12.50's are too wide for the stock wheel width. 285/75-16's are a little narrower (about 11.25") but should still go on wider wheels to fit correctly, although people do put them on the stock wheels...

 

I have the 5.4L triton with the 3.73 limited slip front and rear. Thanks for all the feedback guys. Just wondering is there a good backspacing size that would help with the larger tires ? Thanks.

 

bigred350 - what year is your truck and did you have to put a lift on the front to get the 315's not to scrub? Also how did the 315's effect your fuel milage?

 

My truck is a '97 and it's stock lift at present. I am considering adding an inch or two to the front just to level the truck. I've got a 7.3 PSD and an enourmous "cow-catcher" front bumper (the truck is from Texas) and I think all that weight has caused the front leaf springs to sag a bit.

 

Are you running 315-75-r16?

 

I didn't think those would fit with out a lift on the frontend?

 

Yes, and they fit! Big O had a special on these tires. The manager didn't think they would fit either but agreed to mount them on the front and try it out. I am also running the stock alloy wheels. Like I said though, I have a custom front bumper so maybe that's why they fit. I'm not sure if they would with a stock bumper.

 

Cool...I rolled one up beside my 03's fornt end and It looked like I would need at least 2" lift to Clear my front bumper. I'm struggling to decide between (315s and the 2") or (295s or 285s and no lift). What do you think?

 

Personally, I would opt for the larger tires and lift if need be. I tried the 295's at first and they fit with no problem and plenty of room to spare. That's when I decided to try the 315's. As for the milage, it did fall a bit, at least from what I've been able to calculate. I figured the larger tires (diameter) would make my milage increase since they would effectively raise my gear ratio, but it seems to have had the opposite effect! My old tires which were Yokahama 245xR75x16, I averaged about 16 mpg on the highway. With these bigger tires, I seem to have lost about 2 mpg. The other thing I noticed was that the ride is rougher at high speeds, but better around town! I do get some vibration between 70 and 80 mph and I have had them rebalanced 3 times in the last month. The guy at Big O told me that the bigger tires are harder to balance and that should be expected.

 

Thanks BigRed350 - I'm with you on the "biger is better" I'm just worried the 315's may scrubb... I think I'll get the lift now and decide on the shoe size down the road....I appreciate the advise!

 

Yeah, nothing like the big tires tires to make it look like a real TRUCK! The other obvious advantage is no matter how high you lift the truck, it's ground clearance is only as high as the axles and only the higher tires will lift the axles. So, if your planning on any off roading, keep that in mind.

Mark