245x75's for '01 D2??

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Author Message   John Friederich Posted on Monday, September 09, 2002 - 11:55 pm:    Just got a '01 Disco (8800 miles on it) and don't like the looks of the 'street' tires it came with (Goodyear Wrangler HP, 255x65x16). The wheels are 8x16". There's no mud in NV for the most part, just lots of rock (both fixed and loose) on the old mining roads I like to drive. Do 245's still provide a bit of wheel protection for rocks? Without any slang (if you do use it, please explain, as I'm 'new') - can I use 245x75's without trimming or lift? If I need lift, how do dealers usually look at these as far as warranty is concerned? Please explain any trimming necessary in terms a 1st time disco owner can understand . Vehicle is 80% offroad purpose. Thanks for your help... -John F   Chu Son Posted on Tuesday, September 10, 2002 - 12:27 am:    80% offroad? Wow, that's a lot. The 245/75 will fit fine. chu   Kevin Ta (Smalls) Posted on Tuesday, September 10, 2002 - 12:38 am:    how about on a '98 disco with 60-65,000 miles on it? more of an 5% offroad and 30% street and 65% freeway? i have stock 235/70-16 michelins   John Friederich Posted on Tuesday, September 10, 2002 - 09:31 pm:    >>80% offroad? Wow, that's a lot. >>The 245/75 will fit fine. Yes, my wife & I have no kids and 5 cars, the Discovery was to replace our old ('89) 2 door Dodge Raider which is our camping / 4wheel vehicle. Just wanted to know that 245x75x16's will fit with no negative effects... =John F Las Vegas, NV   Erik G. Burrows (Erik) Posted on Tuesday, September 10, 2002 - 11:36 pm:    245/75's are pretty small for a D2. The stock size is 255/65. I think you may have been looking at the D1 tire chart. The biggest tire you can run on a D2 without major modifications is 265/75, which is what I run, happily.   John Friederich Posted on Wednesday, September 11, 2002 - 08:59 am:    Well, I was thinking that the 245x75's should be about the same width as the stock 255x65's, just a bit taller. For the sharp rocks I encounter in NV, I wouldn't mind a tiny bit narrower. How tall can you go without mods on a DII? Thanks... -John F   Al Oliveira (Offroaddisco) Posted on Wednesday, September 11, 2002 - 09:43 am:    I've run 245/75's and they're okay on the D2. That's what they used in the Trek D2's. You can also go up to 265/75. The 265/75's fit well but they're a little tight. You may need to adjust the steering stops with the 265/75.   Chu Son Posted on Wednesday, September 11, 2002 - 11:29 am:    I'd say the 245/75 is the best fit for stock. It's a little taller, but everything fits without any mods. Your gears are not affected as much, and you don't even have to invert the spare tire carrier. The size gain going to 265/75 is not that much either. chu   Michael Villanueva (Michael) Posted on Wednesday, September 11, 2002 - 11:41 am:    I agree with Chu -- I ran stock on my DSII (2001), then 245s for maybe 5K, then 265s for the past 8k miles. Did serious off roading with both sets. If I had to do it over again, I would stick with the 245s. The additional clearance of the 265s can easily be had by simply paying attention, but worse, the overall drop-off in power performance, the drop in mileage, and the tendency for the vehicle to handle like a boat when you go to a 265 is just not worth it. My opinion is that the 265 following is more looking for looks than any off-road performance. By any quantative measure, going to a 265 will lessen your truck's performance on and off-road. Personally, *now* I think they suck, and now I suspect they are for poseurs; when I get my next traning gig, they are most definitely going out the window. Michael   Al Oliveira (Offroaddisco) Posted on Wednesday, September 11, 2002 - 11:53 am:    Wow... Michael... I got just with opposite with the 245's vs. 265's. But you do get a little drop off in power going to the 265's. I don't notice the drop in mileage going from 245 to the 265's. How were you measuring your mileage? If you went by the odometer your measurement may be wrong.   Chu Son Posted on Wednesday, September 11, 2002 - 12:10 pm:    Mike, what'd u do with your set of 245s? I know you had them for a little bit, and then you must have switched to the 265 for the Hole trip. Correct? I remember talking to Bill and he had mentioned that you had some tires problems. chu   Michael Villanueva (Michael) Posted on Wednesday, September 11, 2002 - 01:57 pm:    I do consistent runs on I40 -- and I25, both routes have gradual rolling sets of hills that just drain approach speed. Using 245s, smoked those hills at 85+. After putting on 265s, maybe 75 -- if a head wind, lucky to break 70. Since the 265s have been on, I have never been able to break 90mph -- not even an issue with stock or 245s. Dealership said nothing wrong with the engine, no check engine lights, plugs good, fuel filter replaced, air filter new, even new MAF. All checks out, but the fact remains, the power change literally happened overnight with the new 265 tires. The odometer consistently reads 4.5 mph _under_ actual speed. Going 70 is really doing 74.5 etc. Verified with my nifty GPS, again the change in mph happened right with the change in tires. Now you may be right about measuring the mileage via the odometer -- idiot me, I did not consider that. Average tank with 245s went from 320--360 to 250-280. Mileage went from 14.5-16.5 to 9.5-12.0 I have not done the math, but intuitively it would seem the altered odometer reading could not account for such a drop in mileage. But.... If someone knows how to figure that one, please post it, I am curious. I think in part the mileage drop was synergistic: Between the OME lift (more air drag under the vehicle) then the KVT (higher approach angle; no airdam) then the additional lift with the 265s likely pushed the vehicle past some physical magic marker. Yeah, Chu, I ran the 245s at HIR. I foolishly aired down, and at the end of the trip, had blown two out. I took that opportunity to switch to 265s. Then using 265s wheeled in the back country here in New Mexico looking for that blasted sea scorpion. Good scrambling I did. The additional lift with the 265s? Not worth the performance lost. Paying attention and choosing a good line would have served me better.   Erik G. Burrows (Erik) Posted on Wednesday, September 11, 2002 - 01:57 pm:    When I went from 255/65s to 265/75s, I had zero milage dropoff (I keep very close track of this, with adjustments for tire diameter change.) Also, the 1.25" additional clearance over the 255/65's is very much appreciated, not to much under the diffs, but under the big ass of my DII. It scoops up a lot less sand these days.   Greg Davis (Gregdavis) Posted on Wednesday, September 11, 2002 - 02:43 pm:    Under normal driving, I get between 14-17 mpg. That's an average. Around town it's about 14-15, on trips it's 15-17 (17's on a good run). ANd this is with 285's. Yes, the difference in power is noticeable, but you learn to deal with it. As far as top speed, I've had mine up to 90 easy and it had more left. I just ran out of courage.   Ho Chung (Ho) Posted on Wednesday, September 11, 2002 - 02:55 pm:    hehe, say you get 15 mpg. if you filled up with 20 gallons, it should mark 300 miles on your odometer. how close is that "300" from the "300" you used to get with stock tires?   Chu Son Posted on Wednesday, September 11, 2002 - 03:04 pm:    The bottom line of what Mike says holds true. The gains that the 265/75 provides vs. the 245/75 is not greater than the inconveniences that arise. As far as mileage and power, I thought I'd gained some mileage at first, but eventually I started knocking a lot more until i regeared. I doubt people at low altitude will have this problem, but I was really getting tired of it. It's one of those things where I was happy to live with it at first, but you realize you're doing a lot more city driving than offroad driving. If bigger suits your sense of style and/or driving better, than so be it, but I'd say that a 245/75 is a good all around size for the moderate offroader. chu   Michael Villanueva (Michael) Posted on Wednesday, September 11, 2002 - 03:43 pm:    Greg: If you have some suggestions for me, I am open to hearing them. I keep good mileage / gas records (have to cause of using the DS for my research work), and the power and mileage drop coincided in time with the installation of the 265s. Clearly you (and others here ) have different experiences. How can we reconcile these disparate data? There is no disputing use of additional clearance; clearance is a good thing, but substantive power and mileage drops.. that is where the conundrum is. I was thinking of installing a plywood plate under the KVT to act as an airflow helper -- like I said above, it simply may be a unique combination of factors: Higher lift (OME and tires) with the high approach angle in the KVT may be inducing horrendous amounts of drag under the vehicle. Plus, in concert with lower gearing (larger tires), those factors may be the culprit. Honestly, I am stuck and could use some alternative thinking. Help me if you can! Thanks Michael   RJ Clayton (Tozovr) Posted on Wednesday, September 11, 2002 - 04:30 pm:    For the two of you who went to the larger size (one guy dug the swap and one hated it), did you keep the same tire if not brand but style (AT/MT/Street)?   Al Oliveira (Offroaddisco) Posted on Wednesday, September 11, 2002 - 05:04 pm:    I went from 245/75 BFG MT's to 265/75 BFG AT's. I liked both but the 265's were much better on the road and seemed to handle better at lower tire pressure. The move from MT to AT could account for the better ride but so could the lower tire pressure needed in the 265's. Off road the taller tire did help and as already said every little bit helps with the D2's huge ass end. There was a loss of power but as Greg already said you learn to deal with it. At first I didn't want to go any taller without going to 4.10's but now the power loss isn't a problem for me and I plan on doing 255/85's in the spring.   Michael Villanueva (Michael) Posted on Wednesday, September 11, 2002 - 05:28 pm:    RJ: I kept the same make and brand: The 245s were Michelin in LTX -- and I went to the Michelin 265 LTXs.   John Friederich Posted on Wednesday, September 11, 2002 - 05:31 pm:    I can't argue that wider is better for mud / sand / soft dirt, but floatation is of no importance to me. Where I always find myself in Nevada is on: Dry creeks - rounded but sometimes big rocks down to pea gravel size. Old mining roads - usually very sharp pointed limestone rocks. Some shale in Central Nevada. For these conditions, I think _narrower_ would be better than even the stock 255's. I've even thought of 235's, but will give the 245's a try if there are no mods necessary. Load range 'E' or not is my next question... -John F Las Vegas, NV   Al Oliveira (Offroaddisco) Posted on Wednesday, September 11, 2002 - 06:22 pm:    There may be a few people who have done 235/85's on D2's but I personally wouldn't do it with the 16x8 rims. I would think the 265's would also do better in the slick rock. I don't know if you have any of that in Nevada. I've been in CO and UT and wider tires in those conditions helped with the slick rock and when aired down they would wrap around the smaller stuff much better than the skinny tires. I'm with you on narrow is sometimes better but I wouldn't call the 265's a wide tire.   Ho Chung (Ho) Posted on Wednesday, September 11, 2002 - 06:24 pm:    after reading the tread, i come to the conclusion that stock tire is best. LOL   Michael Villanueva (Michael) Posted on Wednesday, September 11, 2002 - 06:51 pm:    Yeah, I agree with you on this one Ho. I made a stupid mistake -- and managed to convince myself for all of two weeks that it was the right choice. But the data keeps rolling in: Lousy mileage, lousy pick up and go (compared to what it was before), and lousy power -- particularly in a headwind. Last time we had some really, really strong stuff from the west along the I40 corridor, I could not break 55 -- not a joke. The only two things good about them are (a) the clearance and (b) the fact they make the truck look even more badass!   Steve (Scrover) Posted on Wednesday, September 11, 2002 - 07:02 pm:    Michael, I second that. I went with 7.50R16 XZL (32") with stock gearing. Awesome tires on the trails, but I have a hard time getting there! I'm lucky to hit 55 in 3rd, but the clearance is great and they're certainly badass. Gotta get those 4.1s....   Michael Villanueva (Michael) Posted on Wednesday, September 11, 2002 - 07:08 pm:    4.1s? So I have heard Steve; but a little birdy said even with with change of gearing aint _nothing_ gonna bring back my mileage. Which, now that it is gone, aint so sucky as I first thought. Oh well. No biggie, but frankly, I am surprised at this board. In all the discussions I have watched about tires over the past year, I do not recall anyone calling the 265s on the carpet for their deleterious effect on performance.   John Friederich Posted on Wednesday, September 11, 2002 - 07:13 pm:    Ah, well now, I see the landscape is getting more cluttered... I will have to pull a small camper trailer sometimes, so maybe the 'taller' tire isn't a great idea with stock gearing, eh? I've already (in the whopping 4 days I've had the truck) traveled the 'bad' local jeep trail and didn't put any dings in the sheet metal or plastic bumpers, or scrape a diff (although I was breathing heavy over the bad stretch). I was thinking that 'low' range wasn't low enough (almost) but I'm sure that will change as I get to know the truck. -John F Las Vegas, NV Maybe I'll hold out for a while...   Steve (Scrover) Posted on Wednesday, September 11, 2002 - 07:17 pm:    Not everybody wants to admit the disadvantages. IMHO the gas mileage is a minor pain compared to the performance loss. I have my 235/70s on at the moment and it feels like it's supercharged after driving with the 7.50s for a few weeks. Until I do the 4.1 thing, I'll be tire swapping Friday and Sunday nights! The things we do for love..   Rick Lindgren (Slacker) Posted on Wednesday, September 11, 2002 - 07:18 pm:    Has anyone had problems with the 245's on the DII 8inch rims? They are skinnier than the stock tires and I've heard people complain about constantly smacking the rims because the 245's are so skinny. I'm currently running stock tires so what the heck do I know. Unless you listen to Ho and then I know everything and all of you with non-stock tires suck. Rick   Rob Davison (Pokerob) Posted on Wednesday, September 11, 2002 - 07:43 pm:    only a poseur would care about onroad performance are we playing coy or simply avoiding the obvious reason the milage is worse? your speedometer is lying to you along with the odometer. when you got bigger tires it becan calculating differently. now, it might appear to be "right on now" but that means you were keeping false statistics previously. becasue bigger tires will change the way that shit is working, you dig? i often think this is why land rovers say they are going faster than they are, because, in turn it gives better gas milage and then that looks good (better) on the window sticker. toss on the extra drag from a rack,lift and heavy ass winch bumper and suddenly life has new meaning to me, there's beauty up above and things you never take notice of. you wake and suddenly you're in love... with your disco's gas milage. not rd   Kim S (Roverine) Posted on Wednesday, September 11, 2002 - 07:49 pm:    John, "I was thinking that 'low' range wasn't low enough (almost) but I'm sure that will change as I get to know the truck." I think you're absolutely right. It still works (so far, LOL) but it should be just a smidge lower. That brings us to locking the center diff as well, LOL. Kim   Michael Villanueva (Michael) Posted on Wednesday, September 11, 2002 - 09:21 pm:    "... your speedometer is lying to you along with the odometer. when you got bigger tires it becan calculating differently. now, it might appear to be "right on now" but that means you were keeping false statistics previously. becasue bigger tires will change the way that shit is working, you dig?" No Rob, I do not dig your logic yet; I am sitting with it, and trying, but I cannot quite make it fit. Everytime I follow your logic, using larger tires, which make you seem like you are going slower via the speedometer, but are actually not, ought to be skewing your mileage towards a positive bias. But that is not the empirical evidence I am experiencing. Going from 245s to 265s coincided with one heck of mileage drop -- and I am arguing that a simple causal link between the tire and the odometer as you have mapped out cannot account for such a decline. I think by increasing the radius on my tires, I have changed my power curve; therfore, my engine is operating less efficiently at the same RPMs, and thus I am getting less mileage. My sense of this debate tells me that any cogent answer which can definitively address if mileage is dropping, is staying the same, or is increasing, must take into account the power differential available to the road when using two sets of tires with different radii. Surely we have some engineers here that can map this out? (other than the software ones...) Michael   John Friederich Posted on Wednesday, September 11, 2002 - 10:10 pm:    I would think that engine functions are controlled by things like engine RPM and the MAF sensor, and the computer should be able to adjust for minor tire rolling diameter changes. I'm not sure about transmission shift points, however. Is vacuum still used for this? If not, changing tire diameters should not have much effect on engine performance (and mileage.) Now, I've forgotton my point, if I ever had one. I'm still trying to figure out if changing tires to slightly narrower, taller, will make the LR work any better. It works pretty darn good with the stock tires, now that I think about it. -John F Las Vegas   Curtis N (Curtis) Posted on Wednesday, September 11, 2002 - 11:10 pm:    My mileage dropped from 14MPG to 12MPG when I went to 265's. That does not entirely compensate for the change in diameter (less that 5%) as Rob points out. I think it is a combination of things. I believe Mike is on track, but I do not believe it is not just the leverage from the increased radius. That also is too small of a difference and would really only apply when accelerating and decrease as speed increased. As a cyclist, I have to hear a lot of crap about rotating mass and its effect on performance. I believe this has at least something to do with the mileage decrease. A wheel becomes "heavier" as it spins. Therefore, a heavier tire will naturally result in in greater energy to keep it going and less MPG. The truth is probably a combination of the above items, but is of no real concern. After all - going from a shitty 14MPG to a shitty 12MPG is not that big of a penalty. I think the 265's are a perfect fit and performance-wise are not too bad either. Curtis   Al Oliveira (Offroaddisco) Posted on Thursday, September 12, 2002 - 02:05 am:    "After all - going from a shitty 14MPG to a shitty 12MPG is not that big of a penalty. I think the 265's are a perfect fit and performance-wise are not too bad either. " Thanks Curtis for putting it so well. Aren't the D90's geared the same as the Discos?   Michael Villanueva (Michael) Posted on Thursday, September 12, 2002 - 02:22 am:    Mine went from 14/15 to maybe 10/11 on average. And I guess Al and Curtis think that is not only acceptable, but pronounce such a degradation "perfect fit and performance-wise are not too bad either." Jesus.... Talk about denial ... oops, I mean cognitive reframing. It ain't just the mileage guys.... your DSII power is way down as well. "You learn to deal with it"?? I guess we all have to do stuff to convince ourselves of our wisdom of fundamentally degrading the performance of our vehicles. I am telling you, the 265 Emperor has no clothes! BTW, Rick: I when I ran those 245s I did scuff the rims, but that was my lack of picking a decent line. I do not think I can fault the tires for my driving. The tires did stay put, and I never lost a bead. I think I had aired down to 20 front and rear when doing HIR.   Al Oliveira (Offroaddisco) Posted on Thursday, September 12, 2002 - 03:03 am:    Maybe I am in denial... or maybe I don't look at my Disco as a performance vehicle. When I get an itch for a 155mph vehicle with 282hp, 310 lb/ft of torque and 6 forward speeds I drive my "family 4-door sedan." I only wish that my low gears were lower but until I go to 4.10's I'll be happy with my setup for my driving situations. My top 3 complaints are... 1. Departure angle (it's a D2 after all) 2. Approach angle 3. brake over angle (limited by 100" wheel base and cross member) Notice power, speed and gas mileage are not listed and that's because I am willing to trade that off for #'s 1-3. And yes, I'm even willing to give up some of my crawling speed for an extra few millimeters under my ass end. I have yet to get stopped in a trail because of lack of gas, crawl speed or because I couldn't go fast enough. But the lack of room under my bumpers has stopped me on a number of trails and not in situations that allowed a better line either. My only real denial is me thinking that I don't really need a D90 with stock 265's that I would quickly change over to 255/85's.   Greg Davis (Gregdavis) Posted on Thursday, September 12, 2002 - 09:40 am:    Ho, 275 on a tank. Add in the percentage that my odo is off, and it's around 300. Sometimes it's 250, sometimes it's 280, but more often than not, it's around 265-275. Now, I'm not the first away at the lights, but I'm not the last either. Plus, I keep my transmission in Sport mode. It tends to shift a little better and the engine doesn't "lug" as much around town. Supposedly the "Sport" mode will learn your driving technique and adjust for it, but I can't say for sure. All I can say is that I get better mileage in "Sport" mode than in "Normal" mode with my large tires. Other than that, there's no voodoo to how I drive. Just pretend there's and egg under your pedals. "Easy On- EasyOff". Hell, that works with any vehicle, and from what I've experienced, especially with a Disco. When my wife drives it, she get HORRENDOUS mileage, but it's because of her driving habits. At any given time, one of the pedals is to the floor! Mike, do you have a roof rack? If so, that could be contributing to your mileage. I'm picking mine up at MAR, so I'm sure my numbers will drop accordingly. Only time will tell. Damn, there's that song from the group Asia again).   Ho Chung (Ho) Posted on Thursday, September 12, 2002 - 11:36 am:    greg, so your numbers are the corrected numbers. well then, you got some magic shit going on, cuz that's pretty good!!! and al, i know deep inside you are saying "hunk of shit used to be faster than this with stock tires..."   Ho Chung (Ho) Posted on Thursday, September 12, 2002 - 11:39 am:    but you know, i just realized, what wouldn't we do for happiness? i still believe that my disco drives better than stock sometimes. LOL mind over matter. eh?   Al Oliveira (Offroaddisco) Posted on Thursday, September 12, 2002 - 11:42 am:    Ho, Only when I get passed by a diesel VW Dasher.   Chu Son Posted on Thursday, September 12, 2002 - 11:46 am:    I dunno Al, I think you got the wrong vehicle for the kinda of offroading you're doing. The approach/departure are not the best in the business, but you're pushing your truck way too hard! chu   Al Oliveira (Offroaddisco) Posted on Thursday, September 12, 2002 - 11:49 am:    Chu, I'll have to keep myself in denial until the stock market pickes back up. When ever that might be. Or maybe I'll have to follow Greg's foot steps and lift the D2 up 4.5" and add 9.00r16 XL's.   Ho Chung (Ho) Posted on Thursday, September 12, 2002 - 11:59 am:    damn al, then your disco will look real cute. LOL   Greg Davis (Gregdavis) Posted on Thursday, September 12, 2002 - 12:18 pm:      Ho Chung (Ho) Posted on Thursday, September 12, 2002 - 12:30 pm:      Greg Davis (Gregdavis) Posted on Thursday, September 12, 2002 - 12:58 pm:      Ho Chung (Ho) Posted on Thursday, September 12, 2002 - 01:03 pm:      Greg Davis (Gregdavis) Posted on Thursday, September 12, 2002 - 01:19 pm:      Michael Villanueva (Michael) Posted on Thursday, September 12, 2002 - 01:28 pm:    And what was once a simple tire question, then an engineering problem with real-life variables such as force vectors, wind resistance, power curve, different radii, and actual data, is now reduced to symbolic and iconic communication semantially equivalent to either "Yo Momma!" or "Naada Naada Naada!"   Steve (Scrover) Posted on Thursday, September 12, 2002 - 01:39 pm:      Ho Chung (Ho) Posted on Thursday, September 12, 2002 - 01:39 pm:    well michael, it's just a bbs thing anyways. LOL   Rick Lindgren (Slacker) Posted on Thursday, September 12, 2002 - 01:50 pm:    As I have said before: Usually one short statement = Off the rails, in the ditch, no survivors. Go, Ho, Go.