Another tire question... (or 2)

[jazzman]

SO I have been reading a lot lately

I know my stock explorer can fit a 265/75r16 tire in the wheel wells according to this site.

My question is does going to this bigger tire raise the total height of my ex up much?

I am worried about it still fitting in the garage afterword. I currently have 245/75r16s on stock XLT wheels and would like to try some bigger/more aggressive tires but am wanting to keep it in my garage still.
Also am I crazy for wanting to buy the tires online and have a shop put them on or will they cut me a big break on labor if I buy the tires there too?

Thanks for reading

[fishwish3]

most of the time when you get tires a shop will give you a break on the labor but not always, and when you increase the size of your tires you need to put research into it so you do not throw your speedometer off, it may raise the truck up but not always depending on what part of the size you wish to change

[Blee1099]

It might raise it an inch or stock tires are about 30.5" and the 265/75 are about 31.6" Thus split the difference in the tires.. .55 inches. Alot of tire centers won't install larger tires due to liability issues. So you may run into issues with that.

[jazzman]

All right thanks for the tips, I am not worried about spedo being correct that's what GPS is for. I was just planning to run to wally world to get them installed if I go that route but I guess I see your point about liability issues. I'll have to check around some more probably before I order tires I cant use.

[Carguy3J]

Originally Posted by jazzman

All right thanks for the tips, I am not worried about spedo being correct that's what GPS is for. I was just planning to run to wally world to get them installed if I go that route but I guess I see your point about liability issues. I'll have to check around some more probably before I order tires I cant use.

You should be concerned. An incorrect speedo reading also means the ABS system, and the ECM are getting incorrect vehicle speed info. The Explorer uses speed for the trans shift schedules, so your trans shift points, as well as shift timing,etc... could be off. The ABS might also malfunction. with incorrect wheel speed info.

FYI, the correct factory tire size should be 245/70/16, not 245/75.
Exact circumference (revs-per-mile) will vary among tire manuf. and models, even with the same advertised "size". They are usually fairly close though.
An example tire I looked at on tirerack.com (Bridgestone Dueler AT D695) shows the following:

245/70/R16 has a diameter of 29.5" and "revs-per-mile" of 706.
A 265/75/R16, in this model tire shows a diameter of 31.7" and "revs-per-mile" of 659. This makes sense, since it has a greater circumference (diamter X Pi (3.14), and taked fewer revolutons to travel the same ground distance. It will have a similar effect (though to a lesser extent) as installing "taller" (numerically lower, ie take out 3.73, put in 3.55,etc..) gears in the diff. This size tire will produce a nearly 8% error in the speed seen by your ecm/abs/speedo. This is too much, and will prob. case a problem. It may also reduce your fuel economy, and you will prob. feel a slight loss of off-the line accelaration.
As for vehicle height, you will only see an increase equal to HALF the difference between the two tires. 31.7"-29.5"= 2.2" X 0.5= 1.1" increase in vehicle height.

If your goal, in looking for a "bigger" tire, is increased tread width, then the 265/75/16 is the wrong way to go. A 255/70/16 will have a 10mm wider tread, and a diameter of 30.1" and revs-per-mile of 693. This results in a less than 2% error, and you might be able to get away with this without any electronic correction.

The truelly "correct" way to upsize, for improved handling, is to use the concept called "plus+1" sizing. This would dicate a 245/65/R17. This tire will have the same diameter (29.5") and same revs-per-mile (706), but will have a shorter, stiffer sidewall. This would improve vehicle handling in most circumstances. Of course, this would require new rims.

Keep in mind, if snow traction is why you want bigger tires, than wider tread is not going to help. Wider tread puts more rubber on the ground, and is great for improving dry/wet/and even ice traction, as you increase the size of the "contact patch" For snow, you want a narrower tire, to help it "cut" through the snow instead of "floating" on top. However, there does not appear to be an appropriate size w/ narrower tread that maintains the correct circumference.

Your best bet is prob. to stick with the 245/70/16 factory size.
Also, I wouldn't let walmart touch my vehicle with a 10-foot pole. Find a local tire shop, at least to put them on, if you are going to buy them online.

Here is a link to the Tire Racks's online tech info. Tons of good tire tech:

http://www.tirerack.com/about/techcenter.jsp

[junior426]

While it is true that your ABS and Traction Control systems utilize wheel speed to monitor and take apropriate actions, upgrading to a larger size tire will have virtually no effect, especially given the very minor change in size being referenced here. For most manufaturers, and more importantly on these vehicles, both of these systems work in a manner using a difference in wheel speed between the tires. And with all 4 tires being the same size, it will not change the operation of ABS or Traction Control.

[jazzman]

Hey thanks for explaining it in plain english for me.

I don't want to screw up my car that is for sure. Like a lot of guys I just find myself drooling over the looks of others ex's in the picture threads and want my truck to be badass, too.

My main reason is my tires are almost dead and I am looking for new ones. I'm pretty sure my balder tires are what got me stuck in the snow earlier this winter.

Thanks again!

[JoeCool6972]

Sounds like somebody (carguy) has been listening to the know-it-alls at the big chain store tire shop!

As an automotive technician, I can tell you the main concern with slighlty wider and/or taller tires is the speedometer being off a few MPH. Mine is off 3mph with the 275/55/20 (32"X11" STOCK WAS 245/65/17 OR 30x9.5) I am using.
ZERO PROBLEMS WITH THE ABS! When I worked at the Ford dealer we put lift kits and up to 5" taller tires on all the time.

[Carguy3J]

Originally Posted by JoeCool6972

Sounds like somebody (carguy) has been listening to the know-it-alls at the big chain store tire shop!

As an automotive technician, I can tell you the main concern with slighlty wider and/or taller tires is the speedometer being off a few MPH. Mine is off 3mph with the 275/55/20 (32"X11" STOCK WAS 245/65/17 OR 30x9.5) I am using.
ZERO PROBLEMS WITH THE ABS! When I worked at the Ford dealer we put lift kits and up to 5" taller tires on all the time.

1.) I absolutely I am not "Sheepeople", and I certainly do not simply reguritate anything from anybody; least of all the idiots at most of those chain places. I do the research, and find the facts for myself.

2.) What you have said above causes me to doubt your skills/knowledge as an automotive technician, at least in regards to tires.
a.) While taller tires will have an effect an the speedo,etc..., tire width will not. The primary concern with increased width will be clearance to body/suspension/frame components, primarily at/near full-lock turning.
b.) A 245/65/17 is a 29.5" tall tire, with a circumference of 92.63", not 30", not 32". 30x9.5 is typically a 15" rim size, so not sure where that is coming from. The 275/55/20 you said you are using is a 32.1" tall tire, with a circumference of 100.794". It turns 649 revs-per-mile.

The diff between the 245/65/17 (or 245/70/16, since they are the same height,etc..) and the 275/55/20 is apprx. 8.1%. Which brings me to my next point: We are talking percentages here, not absolute #'s. Therefor, your speedo is not off 3mph (except when your speedo reads 37.03703mph, and you are actually going 40.03703), it is off by 8.1%. This also means that the absolute error increases with speed. When your speedo says 70mph, you are actually going 75.67mph; a difference large enough to possibly get a hefty ticket.

c.)As for the ABS/ traction control. Ok, I accept that the ABS prob. won't be affected, if all 4 tires are changed. (actually 5. don't forget the spare, unless you want your flat tire to result in a torn up t-case/diffs as well) The traction control could still very well be affected. If the front wheels are not moving, 0mph is 0mph regardless of tire size. If the rears start to spin, they will be spinning 8.1% faster then the computer thinks they are. This also means that they will have begun to spin, and reached a certain threshold of slippage that would normally activate the traction control, before the computer even knows it happened. As you may know, it is much harder to stop a tire from slipping once it has stared, then to prevent it in the first place. The slight delay in activation could also mean the difference between sliding into a ditch or not. Yes, this is an extreme example that you may not encounter on any regular basis, but it is still a possibility.

I still maintain that it can also cause long term trans damage. As I said, and many of you know, the Explorer ecm does tranny shifts based on MPH, not nesc. rpm. Therefor, incorrect speed reading to the ecm means incorrect shift points. Again, depending on where/how you drive, you may never "feel" a problem. Or, you may struggle with it everyday. For example, you're going up a hill, trans upshifts early, thinking you are going faster than actual. Now, based on the excessive engine load, it may downshift. Then upshift again, based on erroneous speed readings,etc.... It's called "hunting" and it kills trannys, as it builds up a lot of heat, and wears the clutch packs.

d.) You said you installed up to 5" bigger tires at a Ford Dealer. Well, first of all, what do you mean by 5" bigger? Wider? No, I doubt that, as it almost certainly wouldn't fit. So, that leaves 5" increase in either diameter or circumference. A 5" increase in diameter results in a 15.7" increase in circumference. So, big difference. That would be like going from a 29.5" tire (stock 245-70-16) to a 35.5" tall tire. That is huge. Increasing the circumference by 5" is approx. a 1.6" increase in diameter. That would like going from the stock 29.5" to a 31.1" tire (close to the 265/75/16 the OP was asking about). Either way, making these changes WITHOUT correcting the error (in the ecm, thru a tuner/programmer, in the case of a late model explorer) is very unprofessional. I find it hard to believe a dealer would do with this, with the liability issues and all.

e.) Not that you mentioned it, but I want to reiterate my statement on the effect on gear ratio. While it has nothing to with the speed error, it is something to keep in mind when doing this. Tire size (circumference) definitely contributed to the final drive ratio. Consider the 8.1% error in your case (joecool); if you started out with (and kept) 3.73 gears in the diff, your tire change alone would be the equivalent of installing 3.42 gears with the stock tires. That will have a significant effect on accelleration and fuel economy. In a lighter vehicle, taller gears may improve fuel economy. In something heavy like an explorer, going from 3.73's down to 3.42's may actually reduce fuel mileage.

Finally, to sum it up: If you are going to make any modifications to your vehicle, do the research and do it right. Don't do something just to look "cool" or "badass" if it is going to compromise safety and performance. I'm not saying don't mod, just do it right or don't do it. Todays modern computer-controlled vehicle are very sophisticated. Making one change can have many other consequences that need to be accounted for.
If your changing overall tire diameter/circumference, then you need a programmer to correct the ecm. Period. Anything less is a half-assed, half-finished project.

OOowwww, my fingers hurt now......from all the typing....

[JoeCool6972]

So explain to me then why there are many members here, let alone tens of thousands with other trucks and SUV's with lifts and big tires, or lowering kits with smaller tires and they all haven't crashed yet? If what you said were true, oversize/undersize tires and lifts/lowering kits would be illegal.

As for my tire size ESTIMATES, THEY WERE JUST THAT... ESTIMATIONS.

[CALDWELL]

Now not to thread jack you JAZZMAN...

but your asking about increasing the overall size of the tire ( I.E ) height and width...

Now i hopefully will be buying tires by the end of febuary, and i am looking to go WIDER instead of taller... I want a light A/T tread for light snow and dirt trails...

currently im running the factory 235/70/16 ( Firestone Destination LE ) = I HATE THEM...

i want to switch to 255/65/16 - http://www.tirerack.com/tires/tires....omCompare1=yes

being as im not looking for a taller tire, just a wider tire at stock height... would i really need to adjust my ECU/ECM " which ever your pleasure " to a wider size tire ?

I have no want to lift my X... incase you were wondering why wider, instead over wider and taller lol... i dont go off road enough to really validate lifting... i wanted to but yes i was only drooling lol


Thanks Boys !

[jp450]

I have the 17" rims on my Ex. The stock size is 245/65/17. I do ALOT of soft sand driving in the summer and the stock tires were AWEFUL. My 99 sport with 255/70/16 did very well and out performed my 05 handely in the soft sand. Last spring I needed new tires and researched my best option. I am a dihard Michelan fan so I went with the LTX M/S 255/70/17. This is my 3rd set of these tires on various vehicles. With proper inflation and rotation I expect to get about 100k on them as I have done in the past. With the stock tires my speedo was off about 5 mph @ 65 MPH. So I was only going 60. Now with the bigger tires my speedo is dead on with my GPS and all speeds. I was expecting to have to go and have the ECM reprogramed. The only thing I would do diffrent now is I would have had them not put those damn TPMS sensors back in... I would have done the old pipe trick and stuffed them in the back...

[Blee1099]

Your speedo will only be off by like 3.5% if that (30.5" tire + 3.5%) =31.6. Not enough to make a difference. at 55 it'll be 57 actually.. 65 it'll be 67.

[Carguy3J]

Originally Posted by jp450

I have the 17" rims on my Ex. The stock size is 245/65/17. I do ALOT of soft sand driving in the summer and the stock tires were AWEFUL. My 99 sport with 255/70/16 did very well and out performed my 05 handely in the soft sand. Last spring I needed new tires and researched my best option. I am a dihard Michelan fan so I went with the LTX M/S 255/70/17. This is my 3rd set of these tires on various vehicles. With proper inflation and rotation I expect to get about 100k on them as I have done in the past. With the stock tires my speedo was off about 5 mph @ 65 MPH. So I was only going 60. Now with the bigger tires my speedo is dead on with my GPS and all speeds. I was expecting to have to go and have the ECM reprogramed. The only thing I would do diffrent now is I would have had them not put those damn TPMS sensors back in... I would have done the old pipe trick and stuffed them in the back...

Ok, I'm very confused. Are you talking about an '05 XLT in your sig, or a '99 Sport? What size tires were on what, and what size is now on what? Which one was off 5mph, and now supposedly corrected with the wrong size tires?

[jp450]

Originally Posted by Carguy3J

Ok, I'm very confused. Are you talking about an '05 XLT in your sig, or a '99 Sport? What size tires were on what, and what size is now on what? Which one was off 5mph, and now supposedly corrected with the wrong size tires?

My 05 was off with the stock tires (245/65/17) and was fixed with the 255/70/17's. Sorry about that, had a 2 year old pulling at me when typing

[Carguy3J]

Originally Posted by jp450

My 05 was off with the stock tires (245/65/17) and was fixed with the 255/70/17's. Sorry about that, had a 2 year old pulling at me when typing

ok, now I know what you're trying to say. Only problem is that 245/65/17's aren't stock size for an '05 Explorer XLT. Stock OEM should have been 265/60/17. However they have nearly the same diameter, and therefor your speedo should not have been off. I would trust the speedo before GPS. No way is a 5mph error within the factory specs.

The 255/70/17's you put on should actually be causing a 7.5% error. You should be going faster then the speedo indicates. 70mph on speedo =75.25mph actual speed, enough diff to possibily get a ticket. I would definitely get a programmer to correct the ecm on this. Plus, it has many other benefits.

Again, I would go by your speedo, rather than the GPS, which depends on a signal from multiple sattelites many thousands of miles away. Does the gps system have the capability to be very accurate? Yes, but it is not always perfect, and we, as civilians don't have access to it's full capability. It wouldn't surprise me if the government even introduced slight intentional errors in the signal. Perhaps to prevent it from being used to guide an enemy missle?

Of course, you already bought them, so you're stuck now. When they wear out, I would go back to a 265/60/17. It'll be wider than what you have now, lower profile for better handling, and the speedo should be correct.

Unless a previous owner already had a tuner on it, and set it up for a different size tire?

[Slowlyvverot]

1.) I absolutely I am not "Sheepeople", and I certainly do not simply reguritate anything from anybody; least of all the idiots at most of those chain places. I do the research, and find the facts for myself.

2.) What you have said above causes me to doubt your skills/knowledge as an automotive technician, at least in regards to tires.
a.) While taller tires will have an effect an the speedo,etc..., tire width will not. The primary concern with increased width will be clearance to body/suspension/frame components, primarily at/near full-lock turning.
b.) A 245/65/17 is a 29.5" tall tire, with a circumference of 92.63", not 30", not 32". 30x9.5 is typically a 15" rim size, so not sure where that is coming from. The 275/55/20 you said you are using is a 32.1" tall tire, with a circumference of 100.794". It turns 649 revs-per-mile.

The diff between the 245/65/17 (or 245/70/16, since they are the same height,etc..) and the 275/55/20 is apprx. 8.1%. Which brings me to my next point: We are talking percentages here, not absolute #'s. Therefor, your speedo is not off 3mph (except when your speedo reads 37.03703mph, and you are actually going 40.03703), it is off by 8.1%. This also means that the absolute error increases with speed. When your speedo says 70mph, you are actually going 75.67mph; a difference large enough to possibly get a hefty ticket.

c.)As for the ABS/ traction control. Ok, I accept that the ABS prob. won't be affected, if all 4 tires are changed. (actually 5. don't forget the spare, unless you want your flat tire to result in a torn up t-case/diffs as well) The traction control could still very well be affected. If the front wheels are not moving, 0mph is 0mph regardless of tire size. If the rears start to spin, they will be spinning 8.1% faster then the computer thinks they are. This also means that they will have begun to spin, and reached a certain threshold of slippage that would normally activate the traction control, before the computer even knows it happened. As you may know, it is much harder to stop a tire from slipping once it has stared, then to prevent it in the first place. The slight delay in activation could also mean the difference between sliding into a ditch or not. Yes, this is an extreme example that you may not encounter on any regular basis, but it is still a possibility.

I still maintain that it can also cause long term trans damage. As I said, and many of you know, the Explorer ecm does tranny shifts based on MPH, not nesc. rpm. Therefor, incorrect speed reading to the ecm means incorrect shift points. Again, depending on where/how you drive, you may never "feel" a problem. Or, you may struggle with it everyday. For example, you're going up a hill, trans upshifts early, thinking you are going faster than actual. Now, based on the excessive engine load, it may downshift. Then upshift again, based on erroneous speed readings,etc.... It's called "hunting" and it kills trannys, as it builds up a lot of heat, and wears the clutch packs.

d.) You said you installed up to 5" bigger tires at a Ford Dealer. Well, first of all, what do you mean by 5" bigger? Wider? No, I doubt that, as it almost certainly wouldn't fit. So, that leaves 5" increase in either diameter or circumference. A 5" increase in diameter results in a 15.7" increase in circumference. So, big difference. That would be like going from a 29.5" tire (stock 245-70-16) to a 35.5" tall tire. That is huge. Increasing the circumference by 5" is approx. a 1.6" increase in diameter. That would like going from the stock 29.5" to a 31.1" tire (close to the 265/75/16 the OP was asking about). Either way, making these changes WITHOUT correcting the error (in the ecm, thru a tuner/programmer, in the case of a late model explorer) is very unprofessional. I find it hard to believe a dealer would do with this, with the liability issues and all.

e.) Not that you mentioned it, but I want to reiterate my statement on the effect on gear ratio. While it has nothing to with the speed error, it is something to keep in mind when doing this. Tire size (circumference) definitely contributed to the final drive ratio. Consider the 8.1% error in your case (joecool); if you started out with (and kept) 3.73 gears in the diff, your tire change alone would be the equivalent of installing 3.42 gears with the stock tires. That will have a significant effect on accelleration and fuel economy. In a lighter vehicle, taller gears may improve fuel economy. In something heavy like an explorer, going from 3.73's down to 3.42's may actually reduce fuel mileage.

Finally, to sum it up: If you are going to make any modifications to your vehicle, do the research and do it right. Don't do something just to look "cool" or "badass" if it is going to compromise safety and performance. I'm not saying don't mod, just do it right or don't do it. Todays modern computer-controlled vehicle are very sophisticated. Making one change can have many other consequences that need to be accounted for.
If your changing overall tire diameter/circumference, then you need a programmer to correct the ecm. Period. Anything less is a half-assed, half-finished project.

OOowwww, my fingers hurt now......from all the typing....

tl;dr

[Carguy3J]

Originally Posted by Slowlyvverot

tl;dr

ummm, my internet shorthand must be lacking. I have no idea what you were trying to say there????????

[KevinZwick]

Originally Posted by CALDWELL

Now not to thread jack you JAZZMAN...

but your asking about increasing the overall size of the tire ( I.E ) height and width...

Now i hopefully will be buying tires by the end of febuary, and i am looking to go WIDER instead of taller... I want a light A/T tread for light snow and dirt trails...

currently im running the factory 235/70/16 ( Firestone Destination LE ) = I HATE THEM...

i want to switch to 255/65/16 - http://www.tirerack.com/tires/tires....omCompare1=yes

being as im not looking for a taller tire, just a wider tire at stock height... would i really need to adjust my ECU/ECM " which ever your pleasure " to a wider size tire ?

I have no want to lift my X... incase you were wondering why wider, instead over wider and taller lol... i dont go off road enough to really validate lifting... i wanted to but yes i was only drooling lol


Thanks Boys !

I made the same tire size change. with 235/70R16 and the original michelin tires with 45,000 miles on them (almost at the wear mark), i had pitiful wet road handling but i got 16.5 to 18.5 mpg. When i made the switch to 255/65R16 with BFG long trail t/a, Wet road driving was amazing and still is with 15,000 miles on the tires but now im getting 14.8 to 16 mpg. I dont know if the new BFG tread made the differences or the 20mm more of rubber on the road, but I have had no problems out of anything but a rear axle bearing going out and wearing out my ring and pinion but that started before the new tires. According to police radar and GPS my speedo is off 1mph at 60mph. I would have rather had the stock size back on it if i knew i would lose 60 miles (estimated) on a tank of gas. I hope i helped you out CALDWELL.

[gt183]

Originally Posted by jazzman

SO I have been reading a lot lately

I know my stock explorer can fit a 265/75r16 tire in the wheel wells according to this site.

My question is does going to this bigger tire raise the total height of my ex up much?

I am worried about it still fitting in the garage afterword. I currently have 245/75r16s on stock XLT wheels and would like to try some bigger/more aggressive tires but am wanting to keep it in my garage still.
Also am I crazy for wanting to buy the tires online and have a shop put them on or will they cut me a big break on labor if I buy the tires there too?

Thanks for reading

I have the 265/75/16s on my 05 Ex, and I love them. They do raise the truck up about an inch, but its noticable the first couple times getting in and sitting in the truck. I bought my tires online, and the tire place up the block wouldnt install them cuz they said "they wouldn't fit". Like others have said, they probably just didn't want the liability. I then took it to a place by me called "The Truck Shop" and they had no problem with putting it on. They did do a little trimming, but you can go either way with that.

The tire shop may cut you a break on labor, but I've found that the price saved by finding a good deal online is better. For instance, I was able to get my Pro Comp Xtreme A/Ts for $600 to my door. Then it was $60 to mount and balance (another $60 for the trimming). So $720 with trimming, compared to $880 for the 255/55/16s the first place I went to wanted to charge me for BFGs (I think that was before tax too, but I'm not sure).

O, and if pictures will help you make your decision: