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Car Forum / Dodge / Dodge Trucks / October 2006Taller tires for better MPG ?
Stock size is 245/75-16 If I go up a size to, let's say, 245/85-16s will I get better gas mileage? I'm not looking for much, but if I have to change the tires why not move up to a size that might help. I don't tow, I just carry tools and sometimes some job site materials (concrete, gravel, etc). I know that increasing the unsprung wheel weight will hurt MPG, so I want to go taller not wider, I would love to buy lighter wheels, but I think that would get too expensive. If you think otherwise please tell me where to get cheap light wheels (still load D or E though). From: http://www.miata.net/garage/tirecalc.html Diameters: Stock is 30.5 in With 245/85-16s I'm running 32.4 in (6.3% increase and with toyo tires, I gain 1 pound) With 255/85-16s I'm running 33.1 (8.5% increase - limited tire choice). I could also go with 17s (they are all over ebay), but I think I'll gain more unsprung weight. Of course I'm stuck with "highway" tires, but that's fine. This is a work truck so I don't take it off road. I know the saying, you bought a truck accept your MPG, I'm not crazy about improving my mileage, but when I HAVE to replace a part I always try and upgrade it as best as possible. BTW: what highway tires do you recommend? thanks Peter, You bring up an interesting idea, and I'm curious to see if anyone has concrete info from experience. So the engine turns 8.5% slower with the new set up, right? Let's go with what I think is an optimistic increase in mileage of 5% -- over 40K miles (arbitrary lifetime of work truck tire), that's burning 3077 gal of fuel stock, 2930 with bigger tires. 146 gal. @ $2.50 (ya right) is $365 bucks. My point is that if you're trying to be ecologically sensitive, then ok, give it a try. If you're trying to save money, then maybe there's an alternative. I don't know what you're looking to pay, but stock truck tires are practically given away by the tire shops around here....$70-90 for med. duty set of 4 mounted and balanced, like new condition. You get name-brand quality in construction and name brand ride. Taller tires are also harder on your brakes and will work your tc or clutch more.... Of course I did the same thing I'm recommending, going with a set of 17" take-offs -- a little taller, yes more rim but less tire. Tough to beat OE Michelins IMO for 5 on rims at $100. Sorry if that's too off-topic or off in the wrong direction. Jon > Stock size is 245/75-16 > [quoted text clipped - 36 lines] > > thanks Theoretically, it would seem that having a taller tire would change the "gearing" very slightly and give you better mpg on the highway... Our Ram had 245/16 on it when we got it... the door sticker called for 255... We went to 265/16 and didn't see a mileage difference, but didn't really track it before the new tires.. NOTE: changing tire size WILL throw your speedometer and such off... ours reads 60 when we're doing 63 mph... I'm guessing that it was off by the same amount in the other direction before... If so, the odometer would tell you that the mileage was better with smaller tires because it registered 4% faster/further than you actually went??? >Stock size is 245/75-16 > [quoted text clipped - 36 lines] > >thanks Mac https://home.comcast.net/~mac.davis https://home.comcast.net/~mac.davis/wood_stuff.htm Your idea is sound, but will be harder on equipment, because of the gearing change. Another way to save gas is to buy Load Range E tires. These tires can be inflated to 80 psi, and then you will have less rolling resistance, with the same gearing. Remember the difference on a 10 speed bike between 60 psi tires and 100 psi tires, if not, go test a bike at a local bike shop - and really save some gas! > Stock size is 245/75-16 > [quoted text clipped - 36 lines] > > thanks > Your idea is sound, but will be harder on equipment, because of the > gearing change. Another way to save gas is to buy Load Range E tires. > These tires can be inflated to 80 psi, and then you will have less rolling > resistance, with the same gearing. I believe the 80 pounds is when the truck is loaded to it's max. Operating at 80 pounds m/t isn't going to put much rubber on the road and the truck will ride hard as hell imo. Roy I can't tell the difference in ride at 40 psi or 80 psi. on my 98 Ram 1500 SLT Larime. Of course, it ain't the best ridin' truck, anyway! But I do get another mpg or so (depends on how much highway crusin' you do.) >> Your idea is sound, but will be harder on equipment, because of the >> gearing change. Another way to save gas is to buy Load Range E tires. [quoted text clipped - 6 lines] > > Roy >I can't tell the difference in ride at 40 psi or 80 psi. on my 98 Ram 1500 >SLT Larime. I guess my a.s is more sensitive than yours.<G> Of greater concern is the stopping ability of your truck with the 80 pounds in the tires and m/t. You have a much smaller patch of rubber in contact with the road. Roy >>I can't tell the difference in ride at 40 psi or 80 psi. on my 98 Ram 1500 >>SLT Larime. > > I guess my a.s is more sensitive than yours.<G> You bet it is!!!! > Of greater concern is the stopping ability of your truck with the 80 > pounds in the tires and m/t. You have a much smaller patch of rubber in > contact with the road. > > Roy Stopping???? what's that????  Signature---------------------------- -Chris 05 CTD 06 Liberty CRD Real Trucks don't NEED spark plugs. >>>I can't tell the difference in ride at 40 psi or 80 psi. on my 98 Ram >>>1500 SLT Larime. >> >> I guess my a.s is more sensitive than yours.<G> > > You bet it is!!!! And it's cute too!<BFG> There's a gimmie for wide ride Roy >>I can't tell the difference in ride at 40 psi or 80 psi. on my 98 Ram 1500 >>SLT Larime. [quoted text clipped - 6 lines] > >Roy oh, sh.t... you going to get heated leather seats now, bro? Mac https://home.comcast.net/~mac.davis https://home.comcast.net/~mac.davis/wood_stuff.htm >>>I can't tell the difference in ride at 40 psi or 80 psi. on my 98 Ram >>>1500 [quoted text clipped - 10 lines] >> > oh, sh.t... you going to get heated leather seats now, bro? Gotta tell ya story bro. For me heated seat's are dangerous. I've worked nights most of the past 30 years and never had a problem staying awake while driving. I had left the truck at home and taken Sue's eldo, at about 3:30am on a cold Feb. morning I'm driveing along and figure let me try these heated seats. 5 minutes later I'm thinking these are real nice sooo comfortable. 10 minutes later I catch myself nodding off. Too comfortable. Had the same thing happen a few weeks later. Those were the only times I had ever nodded off while driving. Never, ever will you get me to use them again Yup, I do have a sensitive a.s.<G> Roy > Mac > > https://home.comcast.net/~mac.davis > https://home.comcast.net/~mac.davis/wood_stuff.htm >Gotta tell ya story bro. For me heated seat's are dangerous. I've worked >nights most of the past 30 years and never had a problem staying awake while [quoted text clipped - 7 lines] > >Roy hmm... opposite of brain freeze?? Mac https://home.comcast.net/~mac.davis https://home.comcast.net/~mac.davis/wood_stuff.htm > Gotta tell ya story bro. For me heated seat's are dangerous. Just don't crank up the heat in them after visiting the Chili and Hot Wings diner. >> Your idea is sound, but will be harder on equipment, because of the >> gearing change. Another way to save gas is to buy Load Range E tires. [quoted text clipped - 6 lines] > >Roy While it is true that 80 PSI is required for max load capacity, there is benifits from increase average presure from reduced rolling resistance which can improve MPG. The only real draw back is a stiffer ride on a bumpy road. Tread design and profile plays a roll here too. A 83 series tires (like a 235/83/R16 E) will have less drag and rolling resistance than a 70 or 75 seris. It is also about 1 inch taller than a 245/75/16 too. Finailly, the tread design itself plays a roll too. A smooth tire with little or no cleats will consume less power than one with a "meaty" tread. (look at a semi tire sometimes) Genrally unless you are carry enough weight to need it, there is little or no gain in MPG with pressure over 55 to 60 PSI so even a D range tire running at or near max pressue will roll nicely with a smooth tread. ----------------- TheSnoMan.com > A 83 series tires (like a 235/83/R16 E) will have less drag and > rolling resistance than a 70 or 75 seris. > ----------------- > TheSnoMan.com Where do you find a tire with an 83% aspect ratio??? or 83 series as you call it? oh and while I'm asking questions.....you find that knock sensor yet? just wondering. Signature---------------------------- -Chris 05 CTD 06 Liberty CRD Real Trucks don't NEED spark plugs. >>> Your idea is sound, but will be harder on equipment, because of the >>> gearing change. Another way to save gas is to buy Load Range E tires. [quoted text clipped - 23 lines] > ----------------- > TheAssHoleMan.com Well, well, look what crawled under the door. Tired of spreading false info at the other group and decided to drag your a.s back here? First you have a few questions to answer from the last time you were here. You remember them don't ya? Or are you here for another reason, I figure there is another reason. Your sig looks good. >>>> Your idea is sound, but will be harder on equipment, because of the >>>> gearing change. Another way to save gas is to buy Load Range E tires. [quoted text clipped - 32 lines] > > Your sig looks good. Oh, you didn't address the stopping issue with over inflated tires. Care to take a shot? The key is 'overinflated'. The tires are not 'over-inflated'; they are inflated to spec. >>>>> Your idea is sound, but will be harder on equipment, because of the >>>>> gearing change. Another way to save gas is to buy Load Range E tires. [quoted text clipped - 36 lines] > Oh, you didn't address the stopping issue with over inflated tires. Care > to take a shot? > The key is 'overinflated'. The tires are not 'over-inflated'; they are > inflated to spec. Really? So it is your position that filling your tires to max air pressure and running the truck with no load does not present a over inflated condition with regard to braking and handling? Am I correct in my understanding? Roy https://www.tiresavings.com/tireShop.php?action=findMan2&manufacturer=Michelin&t irename=LTX+A%2FS&season= I own a set. I know what they do. >> The key is 'overinflated'. The tires are not 'over-inflated'; they are >> inflated to spec. [quoted text clipped - 5 lines] > > Roy > https://www.tiresavings.com/tireShop.php?action=findMan2&manufacturer=Michelin&t irename=LTX+A%2FS&season= > I own a set. I know what they do. Great, you know what is on your truck. Too bad you didn't take the time to answer the two questions I asked. Oh, well, seeing as you won't believe me how about you grabbing the little book you recieved when you bought your michelin's. Inside there is a 800#,give it a call and ask what the recomended tire pressure should be with the truck m/t. >>> The key is 'overinflated'. The tires are not 'over-inflated'; they are >>> inflated to spec. [quoted text clipped - 5 lines] >> >> Roy > The key is 'overinflated'. The tires are not 'over-inflated'; they are > inflated to spec. Phil: That ain't necessarily the case. The max pressure stamped on the sidewall is the max pressure at the max load. If your load is less than max, you should run a lower pressure for better road contact, handling and braking. While running the max pressure on the sidewall will not harm the tire it will compromise the ride quality, increase NVH and will also impair the traction, especially under wet or slick conditions. The ideal thing is to weigh the truck at each axle and using an inflation/pressure chart use the appropriate pressure for the load the tire sees. Hope this helps Mike >>>>>> Your idea is sound, but will be harder on equipment, because of the >>>>>> gearing change. Another way to save gas is to buy Load Range E tires. [quoted text clipped - 36 lines] >> Oh, you didn't address the stopping issue with over inflated tires. Care >> to take a shot? Unless they are also at maximum load, they are overinflated. We are not talking about passenger car tires here. SignatureIf at first you don't succeed, you're not cut out for skydiving > The key is 'overinflated'. The tires are not 'over-inflated'; they are > inflated to spec. [quoted text clipped - 39 lines] > > Oh, you didn't address the stopping issue with over inflated tires. Care > > to take a shot? >> Your idea is sound, but will be harder on equipment, because of the >> gearing change. Another way to save gas is to buy Load Range E tires. [quoted text clipped - 6 lines] > >Roy I'd have to go with that.... when our friend got the tires for us they were 8 ply because we tow the trailer... they said "max pressure 65 psi" so I ran them at that.. When we took it back in for rotation, he freaked and lowered it to 35 front and 40 rear... said to go to 45/55 when towing.. Mac https://home.comcast.net/~mac.davis https://home.comcast.net/~mac.davis/wood_stuff.htm > Stock size is 245/75-16 > > If I go up a size to, let's say, 245/85-16s will I get better gas > mileage? In every single case I have ever put larger tires on the result was lower mpg. While the effective ratio should improve it, the engine has to work harder to turn the larger tires. I've yet to see a case where it improved mpg. >> Stock size is 245/75-16 >> [quoted text clipped - 5 lines] > harder to turn the larger tires. I've yet to see a case where it improved > mpg. Miles makes an excellent case here. Some years ago we had a great e-mail list, it was called the RTML, or Ram truck mailing list. Some current newsgroup members were on it. One of the members ran an experiment with his overdrive. He ran back to back tanks of gas, one using overdrive as normal, one with it locked out. He got one MPG less with it locked out. Overdrive on a Dodge is .69, about a 30% reduction in RPM for given road speed and MUCH more than you'll get with a larger tire. One of the other caveats is rolling resistance, one of the major considerations of the factory selection is rolling resistance, and most aftermarket tires don't give this much thought. I've seen people lose two MPG with aggressive off road tread tires. If you use a larger diameter and usually wider tire, you may gain some rolling resistance. Lastly I've seen discussions of axle ratios and fuel economy, too low a ratio and fuel economy suffers, too high a ratio and it suffers again. The discussion I'm referencing took place before automatic overdrives were offered. The synopsis at that time was about a 2.9 final drive was about optimal for fuel economy. This obviously was also well before fuel injection was commonly available. But consider this, most half ton trucks today come with 3.42 to 3.55 ratios standard and automatic overdrives offer a 30% reduction of RPM's and now we're down into the 2.5 range. IMHO, this is mostly for emission control to reduce amounts of pollutants per mile, NOT to increase fuel economy. Maybe with the better atomization of fuel with injection this is the new optimal ratio, it's hard to say, I could be wrong. But if we're already this high in axle ratios, how much could a little taller tire help? Now if you want taller tires because they look better, I'm with you there. Just don't want you to do something expecting one thing and not getting it. >> Stock size is 245/75-16 >> [quoted text clipped - 5 lines] > harder to turn the larger tires. I've yet to see a case where it improved > mpg. I went from 215/75-15s to 235/75-15s on my Dakota and lost a couple of mpg. Ken >>> Stock size is 245/75-16 >>> [quoted text clipped - 9 lines] > >Ken Ken.. before or after speedometer recalibration? I would guess at about 7 or 8% error with that tire change... Mac https://home.comcast.net/~mac.davis https://home.comcast.net/~mac.davis/wood_stuff.htm >>>> Stock size is 245/75-16 >>>> [quoted text clipped - 18 lines] > I would guess at about 7 or 8% error with that tire change... > Mac Tire retailer said recalibration wasn't necessary. I'm going back to 215s or maybe to 225s real soon. Ken >>>>> Stock size is 245/75-16 >>>>> [quoted text clipped - 23 lines] > >Ken We went up 1 size on the Ram and it reads 60 when you're doing 63... yours should have been maybe double that error with 2 sizes... Mac https://home.comcast.net/~mac.davis https://home.comcast.net/~mac.davis/wood_stuff.htm > > Stock size is 245/75-16 > > [quoted text clipped - 5 lines] > to work harder to turn the larger tires. I've yet to see a case where > it improved mpg. What about going to a "slightly" taller tire that is lighter and more narrow like 235/85-16s (I checked 225/85-16s but no one makes them). My current 245/75-16s weigh 53 pounds (Michelin), the 235/85-16s weight 45 pounds (Continental). If not, would at least this help us; go "skinnier" - what about going with 215/85-16s. It's just about the same height, less friction with the road and the tires weight about 18 pounds less than the stock tires. That should help with MPG, right? thanks > > > Stock size is 245/75-16 > > > [quoted text clipped - 15 lines] > the road and the tires weight about 18 pounds less than the stock > tires. That should help with MPG, right? Not always enough to see and you will notice a reduction in traction. SignatureIf at first you don't succeed, you're not cut out for skydiving |
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