theexbrit Posted June 7, 2014 Share Posted June 7, 2014 So, ever since fitting the 33's I've noticed a loss of power uphill & the mpg has gone to she-ite. I was expecting this so no big surprise. Today I thought "what the heck" & I put the 31" tires back on just to see how she ran, holy crap! I couldn't believe how much lighter & responsive everything felt. Steering, acceleration, cornering, everything felt much nicer. Having said that I have to say that the 31's just plain look like crap on the car. Obviously re-gearing would be the solution for the 33's, but I've seen people say that even with re-gearing the gas mileage is still @!*% & the engine revs a lot higher at cruise, also the engine runs a lot hotter. What's the truth regarding re-gearing? Link to comment Share on other sites More sharing options...
Nefarious Posted June 7, 2014 Share Posted June 7, 2014 (edited) Pretty complex question actually, re gearing will make your over all gear ratio the same as factory, so your power will be the same as stock MINUS the increased unsprung rotational weight at the wheels. If your wheels were somehow the same weight between 31-33" and the diff gears were swapped to account for the change in wheel diameter. Technically your power and mileage will be the same minus things like increased wind resistance from added height above and below the vehicle and other factors. This is not realistic, but the closer you can get to that situation the better off you will be. Best approach is to stay with a taller but narrower tire. Some tires are lighter than others as well. I run Goodyear duratracs that are 33x12.5 but they are almost the same weight as many 31x10.5 tires so choosing lighter tires helps as well. Like running a 33x10.5 or something along those lines. Reducing contact patch and friction but mainly tire weight . Also running narrower light alloy rims will help fuel mileage, power and especially handling. Taller over all gear ratio like you get from increasing tire height can even improve mileage on long cruise trips if the engine has enough power to comfortably move the vehicle. I'm not sure what wheels and 33 tires you run but you may want to check their weights anr compare that to stock. The wheel and tire weights also have a massive effect on the handling an how nimble a vehicle is, so that will be the most effective way to maintain the handling characteristics you want while increasing tire height. Basically keep your wheels as light as possible, and if you slightly increase your vehicles power as you increase your tires height you probably won't notice the power difference and you may even find your fuel mileage increases due to the taller over all ratio. That's what happened to me! on highway trips I average about 19-20 mpg with stock 4.63 gears, auto trans, vg33e intake/headers/exhaust, and 33x12.5 duratracs on lightweight 15x7 deep dish alloys. Before the engine swap I had a stock vg30e in good health with 29" street tires , and I only got 17-18 mpg . I run much taller tires and a slightly more powerful motor and my mileage is much better (for a pathy). This is just my experience but it has worked well for me! Going to a 35 or 37" tire I would then look into re gearing as the difference is much more drastic but from 31-33 in my experience can easily be made up for in slight power modifications. Edited June 7, 2014 by Nefarious 1 Link to comment Share on other sites More sharing options...
adamzan Posted June 7, 2014 Share Posted June 7, 2014 When I went from 31s to 33s (the same tires as nefarious), the main power loss I noticed was off the line and on the freeway, I can't tow my trailer that well anymore... I don't have that many hills here so my mileage is still around 18mpg if I drive decently. My plan is to only use the 33's for wheeling trips. 1 Link to comment Share on other sites More sharing options...
Nefarious Posted June 7, 2014 Share Posted June 7, 2014 Or swap in a vg33e and I/h/e it and run the 33s all the time Haha sometimes I think of going to smaller 31s for DDing but 7" lift looks far too silly for 31s lol 1 Link to comment Share on other sites More sharing options...
theexbrit Posted June 8, 2014 Author Share Posted June 8, 2014 I have the steel Pro Comps so that's a lot of weight (plus all the other crap I have bolted on, as Precise1 would say), on the vg33e, auto trans. I'm thinking 32x11.5 like the setup stioc has, on alloys. It still looks pretty good but doesn't have the weight & drag of my set up. Link to comment Share on other sites More sharing options...
Nefarious Posted June 8, 2014 Share Posted June 8, 2014 That's a good compromise actually.32x11.5 or 33x10.5 on alloy rims and u shouldn't notice much if any difference 1 Link to comment Share on other sites More sharing options...
Precise1 Posted June 8, 2014 Share Posted June 8, 2014 I have the steel Pro Comps so that's a lot of weight (plus all the other crap I have bolted on, as Precise1 would say), on the vg33e, auto trans. I'm thinking 32x11.5 like the setup stioc has, on alloys. It still looks pretty good but doesn't have the weight & drag of my set up. What? Just going by what my eyeballs tell me! That would make a bit of a difference (the 32" inch), but maybe not alloys as you are out in bat rock country. Perhaps just more narrow steel rim, the minimum to mount the 32" tires as a compromise? There is a reason I run 31" tires on my WD21; it still drives well with acceptable power, and I can tow with it with the stock motor. I'd much rather invest in under armor than 1" of more clearance... B 1 Link to comment Share on other sites More sharing options...
Nefarious Posted June 9, 2014 Share Posted June 9, 2014 A good set of alloys are actually stronger than steel rims. Depends on the construction style and quality of the alloy. Mine have been through hell and back and before this were on several other bush truck beaters and I have never had a problem with them. Blown up tires, rims are still minty. just my experience, but just stay away from the cheap crappy alloys like Eagles. Link to comment Share on other sites More sharing options...
stioc Posted July 7, 2014 Share Posted July 7, 2014 (edited) Somehow I missed this thread earlier but just to clarify I'm running 32x9.25" tires (235s). I went this route to keep the weight and friction to a minimum. However, the 265s (10.5") look much better and sometimes I wish I'd gone that route because my truck doesn't look as tough with the 235s lol. The advantage of my 235s vs. 265 BFG ATs however is that the former are snow rated, E-load tires and still just a bit lighter than the 265s which are C load tires and not snow rated. BTW I like my BFG AT KOs much better than my previous Duratracs but that's another topic. As for gearing even with the VQ motor I'm still thinking of re-gearing from my stock 4.34 to 4.63 because almost all my trips are fully laden with people and camping stuff and I need more torque. I weighed my truck and I'm a little over the specified GVWR Edited July 7, 2014 by stioc 1 Link to comment Share on other sites More sharing options...
Nefarious Posted July 8, 2014 Share Posted July 8, 2014 Just use good brake pads and you will be fine. Airbags in the rear coils I've been told help a lot when you are a little on the portly side (vehicle wise, lol), I will be installing some of those soon for when I load up to go camping. 1 Link to comment Share on other sites More sharing options...
stioc Posted July 11, 2014 Share Posted July 11, 2014 Nah, I'm convinced some downsizing of tires will cure all mpg and ill-handling issues, it's been proven on the interwebs before. 2 Link to comment Share on other sites More sharing options...
bushnut Posted July 12, 2014 Share Posted July 12, 2014 I don't know what to say 2 Link to comment Share on other sites More sharing options...
theexbrit Posted July 14, 2014 Author Share Posted July 14, 2014 Nah, I'm convinced some downsizing of tires will cure all mpg and ill-handling issues, it's been proven on the interwebs before. Link to comment Share on other sites More sharing options...
SAR Posted July 16, 2014 Share Posted July 16, 2014 Anybody making 33/9:50x15 anymore? BFG did in A/T and M/T. Had a large footprint at real low pressures. Link to comment Share on other sites More sharing options...
stioc Posted July 16, 2014 Share Posted July 16, 2014 (edited) ^ yes they do. Capt Andy here runs that size and I was considering it at one point too. However, after two years of running many trails from Moab to Death Valley I think the 32" tire is a really good tire size for our size (wheelbase) rigs unless you're building a rig to do mostly the black diamond rated trails or above (John Bull, Dishpan, Rubicon etc). The three 32" sizes that speak to me are 235/85/16, 265/75/16 and 255/75/17 - after the 235s I'd say the 265 or 255 are a better size even if with a slight mpg hit. The 235s are a bit skinny especially with 2"+1" lift. On the plus side I can fit it in the factory spare location under the truck. Edited July 16, 2014 by stioc 1 Link to comment Share on other sites More sharing options...
theexbrit Posted July 16, 2014 Author Share Posted July 16, 2014 33 x 9.5 seems a tad skinny to me, it would make it look like the rig is on bicycle wheels. :laugh: I think the 12.5" wide tires are too much friction for the 3.3L motor. I'm going with stioc's suggestions next time & will probably get 32 or 33's x 10.5. Link to comment Share on other sites More sharing options...
SAR Posted July 16, 2014 Share Posted July 16, 2014 I just think wide tires are overrated. A long footprint aids off road traction (with low centrifugal force loads) just fine. What advantages do 32's offer over 31's, in light of disadvantages such as overall gearing, increased unsprung weight, rotational issues, etc.? Does a half- to three-quarter increase in ground clearance make a major difference? In what terrain? TIA. 1 Link to comment Share on other sites More sharing options...
theexbrit Posted July 17, 2014 Author Share Posted July 17, 2014 All tires are not exactly the advertised size, my "31 inch" Kelly's for instance, were actually only 29", so when I added the 33" Duratracs (actual 32.5 inches), it made a big difference in ground clearance under the diff. There are websites that give the actual size of the tire, I think Tire Rack has a chart. It doesn't make a major difference but less wheel revs per mile gives you a small mpg gain on the highway once you get to cruzin' speed. I found the extra 3' or so under the diff & under carriage helped to not get high centered in some rock gardens. Link to comment Share on other sites More sharing options...
SAR Posted July 17, 2014 Share Posted July 17, 2014 (edited) " 3' " That's quite a lift, alas, my wife is but 60" tall. I've had to actually get air to experience that kind of ground clearance. I've never had more than 35" tires with 20" of travel and 17.5" ground clearance. And that was not a Pathy. Edited July 17, 2014 by SAR Link to comment Share on other sites More sharing options...
Precise1 Posted July 17, 2014 Share Posted July 17, 2014 That's quite a lift, alas, my wife is but 60" tall. So more like 5'? (it is only a shift slip away) I just think wide tires are overrated. A long footprint aids off road traction (with low centrifugal force loads) just fine. What advantages do 32's offer over 31's, in light of disadvantages such as overall gearing, increased unsprung weight, rotational issues, etc.? Does a half- to three-quarter increase in ground clearance make a major difference? In what terrain? TIA. I agree, 1/2" ground clearance is not important and argued for better under-armor myself. Likewise with the overly wide tires in general, but in high flotation situations (aired down in soft sand or deep mud) just a little width goes a long way and can easily make the difference between driving out with a tug, or doing a lot of digging... That said, I don't run overly tall or wide tires (10.5x31"), I just run the best tread/compound I can for all of my possible needs. B 1 Link to comment Share on other sites More sharing options...
CDN_S4 Posted July 17, 2014 Share Posted July 17, 2014 ^^ Precise1, do you have any pictures of the 31x10.5 setup? I'm very new at the 4x4 game, and I'm looking around for a decent setup, I'd say 32's max as I'm only planning on a 2" lift with spacers from fleury. What size rim is recommended for this setup? I'm mainly looking for width, typical size being 15x7. Is anyone running 15x10 on a 10.5-11 wide tire? Or would the tire need to be much wider than the rim? Sorry if it's a stupid question, but I'm well versed in car modifying where often the tires are more narrow than the rim, or equal width... please educate me. And sorry for thread jacking, just trying to keep the info consolidated instead of spread over multiple threads. Link to comment Share on other sites More sharing options...
Beatup96 Posted July 17, 2014 Share Posted July 17, 2014 Most who run 31's or taller are running 8" wheels with 3.75" back spacing . IIRC those who've run 10" wheels have had problems , there is a thread around here somewhere on it . Going above 31's will need some lift and 3.75" back spacing to clear the strut perch . Be aware that these wheels will push the tires well past the fenders in a truck with no flares . My next set of tires should my truck outlast the 32/11.5 STT's on it now will be 33/10.5's . 2 Link to comment Share on other sites More sharing options...
CDN_S4 Posted July 17, 2014 Share Posted July 17, 2014 (edited) ^^ Awesome thanks for the info. So can I run 32's on a 2" lift with a 15x8 rim? I'm not worried about the tire sticking out beyond the frame, in fact that's part of what I'm looking at achieving. PS - got pics or link to pics of your current setup? Edited July 17, 2014 by CDN_S4 Link to comment Share on other sites More sharing options...
Beatup96 Posted July 17, 2014 Share Posted July 17, 2014 ^^ Awesome thanks for the info. So can I run 32's on a 2" lift with a 15x8 rim? I'm not worried about the tire sticking out beyond the frame, in fact that's part of what I'm looking at achieving. PS - got pics or link to pics of your current setup? You'll get some rubbing at full lock in forward motion , it'll be a bit worse in reverse . You can trim up some plastic in the wheel wells if that's the case , there are threads on what to do . I just put up pics on the other thread . Link to comment Share on other sites More sharing options...
theexbrit Posted July 17, 2014 Author Share Posted July 17, 2014 (edited) I have the 2" AC lift springs plus a 1" spacer on the front, here's what it looks like with 33's........... These steelies are 15x8 with 3.75 back spacing, the tires are 33x12.5x15 Duratracs. Edited July 17, 2014 by theexbrit 2 Link to comment Share on other sites More sharing options...
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