fitting 31" tires on | Ford Explorer Forums

  • Register Today It's free!

fitting 31" tires on

krazy karl

New Member
Joined
February 26, 2002
Messages
2
Reaction score
0
City, State
Esmont, VA
Year, Model & Trim Level
2000 Explorer Sport
Hey I was wondering how much of a lift would I have to get to be able to put on 31" tires on my 2000 explorer. And what would be the cheapest way, considering i don't have much cash, to get it lifted.
 



Join the Elite Explorers for $20 each year or try it out for $5 a month.

Elite Explorer members see no advertisements, no banner ads, no double underlined links,.
Add an avatar, upload photo attachments, and more!
.





I have 31x10.5s on my sock ride height 96. I get virtually no rub in normal driving but it is EASY to stuff them off road.

You can do a 2" torsion lift for about 50 bucks. Just buy the arrior shackle (PN-WAR153) and stick it in the back and crank your torsion bars. Although I don't know if you would want to crank a whole 2" out of em'. Maybe an 1.5".
 






If you keep your stock rims, you won't have hardly any rubbing (only in extreme compression). If you go with aftermarket rims with any less than 3.75" of backspacing than you will have to trim the bumper (front of the wheel well) for the tires to turn. I can send you pics if you like. No one has noticed my trimming until I point it out. It is very discreet and very easy.
 






Send the pictures, I'd like to see how you did it. I'm this close to putting 31's on my stock '94 and I need a little more convincing that all will be well.
 






I have a '93 sport 100% stock. 31's fit GREAT!! No rub what-so-ever! It looks awesome too! They are Cooper Discover A/t's I think. Pretty cool looking tire. GoodlucK!
 






Mine is a 99, in 99 they came out with the new bumper w/ round fog lights, that is what makes the difference with our trucks.

I will email you the pics later today, when I get home.
 






I'm running 31 10.5 BFG AT KO's on my stock 94 ex Been off roading several times and never had them rub yet. I was a little concerned but I went to the tire shop and they put them on and we played with them before I commited 100%. If you know a good tire shop they might do this for you too. Of course I would have bought the 30's if the 31's didn't fit, but they did and wow they are nice, A word of caution you will be going faster than your speedometer says and at about 70 you'll be doing around 82. Learned the hard way from a Sheriff on the highway:rolleyes: But he was nice enough to understand and no ticket :D :D :D . I will strain your alternator because the transmission is electric and teh larger tires will change your RPM, I didn't notice till we took a trip to Colorado for a ski trip and when I came back the alt was wasted. Could have been its time to go but I know the tires helped it along. It wasn't too expensive to repare and it was fairly easy, good excuse to upgrade to a 130 amp.:p :p :p :p :p :p
Blake
 






How much you will be off depends on the diameter of your original tires versus the new tires. Even if you had the smallest size tires that I am aware of Ford putting on (215 75R15) you should have been only going 78MPH. Either you were going faster than you thought or your speedometer was already off to begin with. You would have to have had 26.5" tires to have been off 12 MPH at 70 MPH. You can get another speedometer gear so that your speedometer reads correctly and your transmission shifts at the right points. This only applies up to '97. After that you need to get your PCM reprogrammed or buy an electronic adapter. Your alternator going out had nothing to do with your larger tires. Yes, your transmission is electronically controlled. It doesn't mean that it runs on electricity. The solenoids inside receive the proper voltage to either open or close depending on the gear you need to be in. The extra shifting due to taller tires isn't going to put any extra (measurable) load on your alternator. Your alternator's only function is to keep your battery charged. A few extra shifts isn't going to drain your battery.
 






Either you were going faster than you thought or your speedometer was already off to begin with. You would have to have had 26.5" tires to have been off 12 MPH at 70 MPH


Do you have a formula we can use to figure how much we are off. I have wondered, especially for the odometer to figure for gas mileage.
 






Sorry I don't mean to give anyone bad info, that is what I was told so I guess they are full of who-ha! :shoot: :D All I know is I had to replace my alt guess it was just it's time! The Sheriff.... I never SAW the radar, it's what he TOLD me. Cruise was on 70 mabye 71 but I tried it later with the wife pacing me in the 99 Grand Am and wasn't near as fast as he said could be that both vehicles speedometers are off but he was the one with the "precise measuring device" for speed :rolleyes: One quick question (I don't really want to stray from the topic) but why when I was going through the Mts of CO did I feel as though I was driving a 4 banger with full cargo. My ex just couldn't keep up to the speed limit! Do larger tires really bog the engine down that much?
:bounce: :bounce: :bounce: :bounce: :bounce: :bounce:
 






Do larger tires really bog the engine down that much?

Depends what gearing you had before the upgrade. You can roughly figure it out. Divide the old tire size by the new tire size. Then take that number multiply your gear ratio by it and that will roughly give your new ratio. If you started out with 3.27 that would really cause you X to be bogged down. I have 3.55 and I can notice it but it is livable.

29" / 30.6" = 0.9477

0.9477 x 3.55 = 3.36

New ratio is approx. 3.36:1
 






Originally posted by Blake D
. . .why when I was going through the Mts of CO did I feel as though I was driving a 4 banger with full cargo. My ex just couldn't keep up to the speed limit! Do larger tires really bog the engine down that much?

Larger tires will lower your overall gear ratio. More than likely though what you were feeling were the effects of altitude. Colorado is a pretty hight state (altitude wise) particullarly western Colorado. For every 1000 foot in elevation you go up, you loose 3% of your horsepower. Using the OHV as an example, it would be putting out approximately 118 horsepower (at the flywheel) at 10000 feet elevation which is real common in Colorado. Add the extra weight of cargo, the taller tires and the altitude and it would definately feel like a 4 cylinder. Even my SOHC felt like a small 6 cylinder at the heigher elevations last summer when I had 5 people and a full load of cargo.
 






Originally posted by addkev
Do you have a formula we can use to figure how much we are off. I have wondered, especially for the odometer to figure for gas mileage.

You sort of answered your own question. You would use the same formula that you use to determine your new gear ratio, except you would divide your indicated speed by your ratio and apply it to your speedometer. Using your example (.9477), if your speedometer said you were going 60 MPH, you would actually be going 63.3 MPH. Going the other way, if you know how fast you want to go (say 60 MPH), you would instead multiply it by your ratio. So if you want to go 60 MPH, multiply it by .9477 to get 56.8 MPH. That is what your speedometer will say when you are actually going 60 MPH.

You can do the same thing with your speedometer gear to determine the new one you would need. For instance if your stock gear has 20 teeth, you would multiply it by .9477 and get 18.954. You would need a 19 tooth speedometer gear to make your speedometer and odometer read as close as you can get it. You would still be off by .2% but not even the speedometer is that accurate.
 






i have 31's since new , i ordered my x w/ the smallest tires they offered at the time cause i knew they were coming right off, my speedo is off by 10% = 1/10th of a mile, years ago i had a trooper friend of mine clock me when i had the cruise pegged at 70 and he said i was doing 77
 






You can do the same thing with your speedometer gear to determine the new one you would need.


I wish it was that easy, the 98+ are computer controlled, you have to get the chip re-programmed for the new tire size. Since I live in the middle of no-where, I can't find a dealer that will do it for me. The local FoMoCo, won't do it because they say 31" tires aren't authorized. Blah, blah, blah...


Thanks, for answering my question, I thought the same ratio would apply but wasn't sure.
 






Featured Content

Back
Top