any one tried putting bigger tires on 2004 F150. I want to put 285 70 r17's on mine when it gets here. I am assuming that sence they are only about a 3/4 inch bigger diameter and and 1/3 inch wider than the tires on the 18 inch rims ford offers as stock they should work. the only thing that concerns me is when turning sharp they might rub.

 

If it did rub, the 2 inch lift spacers mentioned on another thread should do the trick.

 

I looked at those lifts. considering them. do those lifts give any more ground clearance on the front end. and I wander if they will affect the handling in any way good or bad. they say it installs easily in 1.5 hours. I wander if it will be easy enough to install I can do it my self.

 

There was another thread about this, but you have to be careful of the width too.. not only in the front but in the back now that the shocks are on the outside. You might need to add more backspacing and get aftermarket wheels.

 

Thought some here might find this pic from a thread on the Ford Truck World forum of interest:

http://www.fordtruckworld.com/forums....ten?id=200153

To me, the XLTs abscence of wheel-lip moldings does leave a little too much empty space for the opening. It would be interesting to see if the FX4/Lariat wheel-lip moldings made sufficient enough difference, that the same wheel & tire combo proportions looked *correct*. One of the upsides of not having those wheel well lip moldings, is that you have extra room to mount bigger meats!

Here is a related thread on lifting 2004s: http://www.fordtruckworld.com/forums....ten?id=201888



FoMoCoFoMe

 

Just curious to know what others might be planning in the way of lifts, wheel & tire upgrades. How much lift would look good and how big on the tires would you consider? Me? I was thinking 4-6" of lift would be as much as I would consider, and tires of maybe 33x12.5 or 35x12.5. Thoughts?

 

there is a 2.5 inch lift for the front that will allow up to 35 iinch tires. I have looked at the rear and it looks like you would not lift it at all for 35 inch tires. I am not sure about the wider tires though might cause problems even with a lift I didn't look how close those outer shocks on the rear sit to the tire hopefully not to close. I am probably going to put the 2.5 inch lift on the front end and put 285-70-r17's on mine thats about 11 5/16 inches wide and 32.7 inches tall. I think that is plenty for me unless I can find a after market set of 4:10 gears for the rear end of my truck. then I might go bigger. but thats some time down the road I am sure.

 

Well, considering that I'm pushing the envelope already at $36,000 for a damned truck, I might just stick with the Daystar 2.5 inch spacers for the front to level that sucker out and leave it at that. At least for a while.

 

Interesting thought Jason, as I do think the less you have to mess with the suspension geometry, the less you are going to be forced to compromise on ride quality -- which most would agree, is one of the better advancements of the new F-150. I am sure it won't be long before someone here see how much tire it takes to fill those wheel mongo sized wheel wells!

 

I'm considering the daystar lift for the front and some 35's in the spring (If it will actually fit). What advantages will I lose by going with a larger tire and only having the 3.73 limited slip as opposed to say a 4.10 ratio?

 

putting the bigger tires on is kinda like lowering that ratio your rear end. when before it had to turn 3.73 turns of your drive shaft to one turn of your reat tire. now the bigger tire travels a larger distance on one turn ot the tire so the drive shaft turns less turns to travel the same distance. this is also why your speedometer will be off. this is my understanding of why a bigger ratio is needed on bigger tires. I do believe this is also why ford lowers the tow capacity by 500 lbs when you pic the bigger 18 inch rims and tires. which are about 1 inch bigger in diameter. if this is true you can figure on decreasing your tow capacity by 500 every inch bigger a tire diameter you go. I am no expert on this If I am wrong on any of this will someone who knows more let me know. thanx

 

Taller tires do effectively change your final drive ratio. For most, the trade off will between fuel economy and power (or towing/hauling ability). Selecting the correct ratio will allow your motor to utilize the power band that is best suited for the job. If your concern is towing and off the line response, then you will want a lower ratio (numericaly higher) gear to insure you are finding the portion of the power band with the most torque.

The trade off also invovles quickness (i.e. zero-to-sixty, or quarter mile elapsed times) vs. top end speed potential. A drag car may be ideal with 4.88 gears, whereas a Salt Flat car, which has several miles to get up to speed, would be doing just the opposite, in order to optimize the gear ratio selection for its intended purpose. While not a concern for either, the drag car is designed with no regard for mileage, whereas the Salt Flat car would likely get much better mileage, but moves comparitively slower, untill it gets up to speed. Quick = thirsty. Slow = thrifty.

When I was involved with rock crawling in a Jeep, many thought the ideal was a final drive ratio as near to 100:1 as possible (that number being the 1st transmission gear ratio x the transfer case ratio x differential ratio). The idea with rock crawling, which is not too unlike towing, is to maintain your forward momentum. Remember, a body in motion tends to remain in motion...

By selecting the proper gears, you have most of your available engine torque to keep you moving forward. You are trying to find a gear ratio that keeps you from having to 'gun it', in order to keep the r.p.m.'s up enough, such that you are not 'lugging' the motor. Doing this after you buy your truck ain't cheap! It also isn't a *need* for the average Joe. Start lifting and adding really tall tires to a 4x4, and you will soon find yourself buy new gear sets for BOTH the front & rear differentials. Cool has its cost.

 

thanx for the info , pretty much what I thought. I was wandering if any one knew how to calculate how much the biger tires affected the rear ratio. example if I wanted to keep my final drive ratio about the same but wanted bigger tires. example raising my tire sise by x inches lowers my ratio by y amount. I bet if I sat down and tried to figure this out I could. after all the diameter of the tire is the distance the tire goes in one revelution. if I go to a bigger tire I should be able to calculate the diameter of it and figure the percentage of increase and that percentage could be used to calculate the decrease in ratio. I doubt it would be completely acurtate but it sounds like it would be a good educated guess. any one have any better info on this that would be cool. thanx

 

You can just look here... find your tire size and ratio and than go to the new tire size and you can figure out what you need to be the same...

http://www.4wheelparts.com/Tirel_Gear_Ratio.asp

 

thanx for the link that saved me alot of calculateing. according to that chart I need to get me a set of 4.10 gears for my o4 whan it gets here. I will probably have to wait a long time for the after market guys to come out with one. I am getting a 4 weel drive I am guessing I have to change a gear in the front drive to match the front to the rear.