new guy here, i've read alot of stuff on here but couldn't find much on the tire upgrades for the 4.6 v8 with the 355 gear ratios. i have an 06,f150 4x4 xl and it came with the 235/75/17's and i found a good deal on the 275/65/18's tire and wheel package. i don't know if my setup can handle that wheel & tire upgrade. i don't think fitment is an issue as it comes stock on alot of other models but none have the 4.6 or 355 gears. i would think a v8 could handle it but i have fried some engine bearings and toasted a tranny before ( years ago ) going over the recomended tire size on vehicles and am very leary now because i bought this new and i want it to last a long time. i've been told i could reprogram the computer at the dealership for the upgrade to correct the speedo but not sure if that will help the tranny or motor at all.any feed back welcome.

thanks
mr.g man

 

That's a 30.87" to a 32.07" increase in overall diameter plus the section width and the weight increase. Your truck can handle that...but at what penalty? Slightly sluggish off the line. Trans shift points off somewhat. Speedo almost 4% slower than your actual speed. MPG hit too.
3.73 hears would be great...but a tune would probably help also...especially since you could change the tire size to calibrate the trans. I think you'll be ok. If you tow at all then you'll really want to explore gears or a tune.

 

i'm not sure what you mean by " a tune ". if your refering to reprograming the computer to adjust the speedo ( 85 dollars at the dealer ) i would gladly do that,,, when i asked the dealer if it would also help the tranny too he vaguely replied, ya it will fix all that. i was'nt too reasured,,, i would have liked a better explanation than that, but thats what he said. i don't work the truck at all except for pulling a 15 ft aluminum boat ( about 1 thousand lbs ) once a week in the summer months. if you can believe this , some people have told me i could improve my gas miliage with a bigger tire, ( go figure ). i guess i'm hoping some guys that have done this will chime in with some experiences, pros & cons, etc. thanks for the come back, that helped somewhat .

 

It will be fine. Your mpgs will fall off though.

 

the 04-12 trucks come with 32" tires (31.7") from the factory

those tires will fit fine. motor/trans will be fine as well

 

He is referring to a tuner to help adjust the speedo, tire size, and shift points. This will decrease the lose of MPG's and improve the response from the truck overall.

Your truck should be fine with the new tires but you would most likely see some power lose but that is about it. I would not go any larger.

 

Tuner info:
5 Star Tuning | Custom Dynomemeter Chassis Tuning Products and Services

 

hey guys, thanks for your responses with the info & vote of confidence on this issue. i haven't had to spend a dime on my f150 in 6 yrs other than routine maintanance and it was time for a face lift. tires & steel painted rims are showing their age and this upgrade to the 275/65/18's and some nice alloys i feel will perk her up nicely. all your comments helped put me at ease with this decision and i assure you that i will enjoy it all that much more." a tune " will happen shortly after install and i will be one happy camper. thanks again ! mr.g man

 

I missed the fact you are doing new wheels too. You may not lose much power at all because you are putting on wheels that weigh less then the original ones.

 

well i finally pulled the trigger and did it,,, hit the car wash first, then to the tire shop for the install, then off to the ford dealer 2 blocks away for the computer flash, ( 53 bucks at the dealer, money well spent in my opinion. the tech explained that it was more than a speedo and trans adjustment but that they download all the latest updates for alot of the other functions,,, ecm , this ,that, and the next thing. i didn't understand half of what he was talking about but it sounded like a good investment to me.) he said the truck will be learning everything from scratch again for the next few trips i take. oh, and each tire ways 8 lbs more so that lighter wheel theory ,,,well, i'll keep you posted on the fuel consumption. ouch , i just paid 49 dollars for 12 gals, of gas. thank god i ride a honda too ! smilin ear to ear,,, i just love what this upgrade did for the truck, thanks again.

 

OK the tires weigh more but ask what the wheel weigh of the old is compared to the new. I would guess there is at least a 5lb difference making the tire weigh nothing. I also wasn't thinking about fuel that will be different I was more thinking about power of the truck off the line and the noticeable difference.

 

good point coskid on the wheel & tire weight kinda breaking even,,, as far as noticing power loss, driving around empty and just babying her it felt pretty much the same. i did notice a smoother ride and a feeling of way more traction ( wider tire ) . a downfall that was quite noticable ws the roll resistance factor. coming off the highway i used to easily glide all the way to the toll where as with the new tires i had to give it some gas to make it. but it also could have been the computer relearning how i drive, before it seemed like it stayed in overdrive when i would let off the gas and it would just coast.this time it felt like i had the jake brake on when i let off the gas. ( slight exaggeration, jake brake = engine brake ) lol. the s turn also seemed to slow the truck down more. time will tell, i'll give at a few weeks before i start doing the math, and try to post a pic of my upgraded babe, oohhh ya,,, sweet !!! i guess size does matter, its amazing what an inch can do , lol.