BF Goodrich Commercial T/A 10 ply highway tires. These are the SAME tires and rubber as on the long-haul highway trucks, just in a 16" rim size. Load range E, 80psi sidewall max, 2900lb capacity per tire. And they ride perfectly square on the roadway when unloaded (exactly as they are supposed to) while the ride isn't noticeably tougher.

Interesting. I am having a set of load range D tires (Pirelli Scorpion ATR) put on the 16" alloy wheels this week. They have a 60psi sidewall max. Would you recommend I run them at 60psi? I was figuring on not running the max inflation unless I was towing, maybe keeping them at 45psi or so.

- Chris

It is a personal choice, based solely on the ride quality, and whether or not you believe that a tire that has a max rating of 60psi (or 80) would be severely underpressured at the "door sticker" 32 or whatever it is. I have gotten into this debate before and tried to explain why running ANY tire at 10% or greater under the sidewall max should be considered lunacy, and nobody listens.

The facts are this: Underpressured, a tire will flex more on the sidewalls than it should. The sidewall is the weakest part of the tire casing. Excessive flex builds heat, that the tire may not be able to shed. Excessive heat leads to glue failure, and the tire will separate and fail. This can cause loss of control or death.

It is MUCH better to run a tire at 10% OVER, than 10% under. A hard tire will not flex as much, and modern radial tires WILL NOT BULGE and wear the centers out, unless you are running extremely wide tires. At 215 - 235 widths, you should be just fine. I know I have been. I always run all my tires at the full sidewall max, and I have never once had center wear instead of the entire tread wearing evenly. What I have had, is on my Jetta TDI, both the inside and outside shoulders wear off on all 4 tires. I had a tire shop try to tell me that it was caused by a bad alignment. That would only wear one shoulder, not both. That wear was caused by driving like I'm auto-crossing, taking every curve at the max G-force that I can get away with within the laws of physics. Running my tires at full sidewall allowed them to perform at their best when I was demanding the most from them.

Your mileage may vary.

I agree, I run my stock goodyears at 42 out of 44 max. I'd put them up to 44 but the TPMS complains about high pressure at 44 and it gets annoying.

Can that be recoded? I have the ability to do all sorts of cool OBD stuff to my cars, it's all a matter of the right software. Since I have a Vag-Com interface, I have all the hardware I need to get into the ECU normally. I'm going to be the happy owner of a TPMS EVIC in a few days, so this is important especially with my tires being at 80psi. Not everyone likes the PASSENGER CAR soft-as-butter badyears on our SUV mini-trucks.

I've heard it can be changed at the dealer with their DRB or whatever.

Geordi,

My stock EVIC reads tire pressure up to a max of 51 psi. I run my Load E tires at 70 psi, but I cant tell on the EVIC !

B

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06 CRD LTD - Suncoast TC- Shift Kit - Spicer UJ - FRKNLIFT - F37 - Magnaflow - 22.0 City - 24@65MPH - Fumoto F-102 - AUX T Cooler - Tank Lift Pump

You mean it doesn't beep when you start the car? Or all the tires just say 51?

all tires show 51 psi

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06 CRD LTD - Suncoast TC- Shift Kit - Spicer UJ - FRKNLIFT - F37 - Magnaflow - 22.0 City - 24@65MPH - Fumoto F-102 - AUX T Cooler - Tank Lift Pump

hmm. I was wondering about an upper limit for the transmitters... That sucks, if it's true for mine too. What year is your KJ? I have an 05, but the Evic is from an 06 Liberty. Shouldn't matter, there is only one part number for all the Liberties, apparently of any year. *shrug* My current EVIC is from an 05 Grand Cherokee, so the temp doesn't work. that's one thing I'm trying to get the right unit for too, in addition to the TPMS.

Glad to see I wasn't the only one that thought of putting load range D or E tires on this beast! In the end, my primary concern was traction in bad weather, and greater width for better stability, so I went with 245/70's that weren't available in an LT rating.

Having the tires at max inflation pressure is one of the nine "commandments" or basics that they teach on gassavers.org, the simple things that can net better fuel mileage without resorting to some of the more extreme methods used by the hypermilers.

The people in the hobbyist electric vehicle community have long known about LT tires, sidewall flex, inflation pressure, and rolling resistance. When you're only carrying the equivalent of 1/2 a gallon of gas in your battery pack, anything to maximize the efficiency of the vehicle helps!

I lost the link sometime back, but one of the EV gents had a webpage with a rolling resistance calculator. By putting in your vehicle parameters - weight, gearing, approximate aero cd, etc - and the size tire, it could show you what the most efficient tire size for your vehicle was.

And the big factors in the calculation seemed to be inflation pressure and sidewall height - the shorter the sidewall, less flex, and lower rolling resistance - with all other factors being equal.

Apparently, the best situation would be to find an LT tire in load range E with a shorter than normal sidewall.

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Mitchell Oates
'87 MB 300D Diamond Blue Metallic
'87 MB 300D - R.I.P. 12/08
'05 Sport CRD Stone White
Provent CCV Filter/AT2525 Muffler
Stanadyne 30 u/Cat 2 u Fuel Filters
Fumoto Drain/Fleetguard LF3487 Oil filter
V6 Airbox/Amsoil EAA Air Filter
Suncoast TC/Shift Kit/Aux Cooler
Kennedy Lift Pump/Return Fuel Cooler

So I guess 18" rims or even bigger would be a help as well... And I thought everyone was just doing it for looks...whodathunkit

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It may be that your only purpose in life is to serve as a warning to others.

06 CRD Sport
Built 5/11/06
Jeep Green
Rocklizard diff cover
V6 Airbox

Well, probably 99% of the people that do ARE doing it just for looks, and if you started talking to them about sidewall flex and rolling resistance would look at you as if you were speaking in tongues.

Hmm it's been a few years, but I seem to remember that if you went with larger rims and same overall diameter tire (ie, drastically shorter sidewall), the gents RR calculator DID show an improvement in rolling resistance.

But for doing it as cheaply as possible, then LT rated 60 or 80 psi tires in LR D or E would be much simpler than swapping out rims as well.

Also, with those huge rims and rubber band tires, there is a point of diminishing returns. You also have to look at the weight rating of the tires.

A gent with Goodyear's EV program told me many years ago about weight ratings and rolling resistance. He said low rolling resistance tires won't do you a bit of good if the tire's weight rating is maxed out supporting the vehicle.

He said to get the max reduction in rolling resistance, that vehicle weight should be 60% or less of the combined weight rating of all four tires. As long as you were below the 60% point, you'd get good results from tires designed for low RR. Above the 60% point, it wouldn't matter how well the tires were designed, they'd be seeing so much flexing for just trying to support the weight of the vehicle that everything else would be lost in the noise.

And that's where the LT tires would have an advantage again - an LT225/75 LR E tire is rated for over 2600 lbs. And as far as treadwear, those bloody things usually wear like iron.

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Mitchell Oates
'87 MB 300D Diamond Blue Metallic
'87 MB 300D - R.I.P. 12/08
'05 Sport CRD Stone White
Provent CCV Filter/AT2525 Muffler
Stanadyne 30 u/Cat 2 u Fuel Filters
Fumoto Drain/Fleetguard LF3487 Oil filter
V6 Airbox/Amsoil EAA Air Filter
Suncoast TC/Shift Kit/Aux Cooler
Kennedy Lift Pump/Return Fuel Cooler

I get the best fuel econ if i leave it in the garrage! HA!

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2008 Tacoma:
4.0-liter DOHC EFI V6 with VVT-i ... 236hp 266Ft-lbs
265-70R16 BFG Rugged Trail (stock).... Rear Locker (stock)
Bilstine 2.5" lift front + ProComp AAL 2" lift rear
LIFT #s Front engine skid 12" @Rear Diff 10.5" @running board 21" @tx case 16"
6spd Manual Tranny
http://o8k.ifp3.com <-- My Photo gallery

What do you mean, you get 0 miles per gallon!!??

thats why i said best economy and not mpg. =D costs me nothing to let the Libby just sit in my driveway.... but yes that does make for rather poor mpg i suppose... or would it be infinity... ok my head hurts now

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2008 Tacoma:
4.0-liter DOHC EFI V6 with VVT-i ... 236hp 266Ft-lbs
265-70R16 BFG Rugged Trail (stock).... Rear Locker (stock)
Bilstine 2.5" lift front + ProComp AAL 2" lift rear
LIFT #s Front engine skid 12" @Rear Diff 10.5" @running board 21" @tx case 16"
6spd Manual Tranny
http://o8k.ifp3.com <-- My Photo gallery

last week I took a trip to somerset KY. on the way up I drove 65 and babied it on the hills as well as drafting as much as possible. MPG up 23. on the way back I drove 80 and got 25 all hand calculated. Since putting the 245/70 tires on I don't know how far off my true speed is from the gauge. I have to go to sevierville tomorrow and will try a leg of the trip going 56mph just for comparison. strangely I used to routinely get 28-30 HWY last year running b100-b20 during the summer. but I have dropped down to a lower % for the winter. When I drove with veggy blend for the summer the mpg was 22-25.

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Manure green 2005 CRD sport4x4, GDE Hot tune, Cat Gut, OE skids, Draw tight hitch, Duramax lift pump, 160K on multiple varieties of fuel, XM radio, Escort live with Redline, fog light mod, GPS, Icom IC7000 all band radio call sign KC9QPF, Grabber AT2s on Soft 8s, FIA grill blanket.

with our new 245/75/16 I noticed the speedo reads lower now by a few mph, but the odometer seems to be dead on.

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http://www.Colorado4Wheel.com
"Its not about what you can DO with your Jeep, its about where you can GO with your Jeep."
Knowledgeable - But Caustic

#!"¤!#¤!#%!#¤# BEEP!#¤!#¤!#"#!

I have that single beep when I start the engine. EVERY SINGLE TIME. Why me oooh why meeeE????? :(

I have an 03 CRD Sport with no EVIC installed. I suspected the beep was coming caused by a bad sync between seat belt sender and engine start sender. So when the engine started it polled the seat belt sender and sent out one beep before it detected the belts were in ok.

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L.O.S.T forever!
Silver 2002 Skoda Fabia TDI, 235,000km
Former car: Jeep KJ 2003 CRD

DIESEL - saving millions of liters of petrol every day!

Quite a lot of that variance could be the crap winter fuel. Sorry for that. In the south here, I don't think they ever get a full batch of winter fuel, but it might get mixed in the delivery pipes a bit. You did get good mileage on your 80mph run, about what I've been measuring too. What size tires do you have?

Also, according to my GPS, my speedo is almost dead-on now, don't know about the odometer. If the odometer is reading high, that would explain a lot about why I think the mileage should be better with these larger tires.