Wheel Nut Torque

I was going to pull off my iMiEV front and back wheels and see if my Gen1 Insight spare fits and thought I'd first look up the tightening torque for the wheel nuts. DUH! Can't find it in either the owner's manual nor my version of the workshop manuals CD which is missing the 'Specifications' portion. My old Saab needed 60ft-lb whereas most of my other vehicles use 80ft-lb. Anyone have this number (and where did you find it)?

From the European Tech Manual (M131100030098900ENG):

SERVICE SPECIFICATIONS

TIGHTENING TORQUE

Standard value
Wheel nut N·m 98 ± 10


STANDARD BOLT AND NUT TIGHTENING TORQUE
Thread size Torque N·m
Bolt nominal diameter mm Pitch mm Head mark "4" Head mark "7" Head mark "8"
M5 0.8 2.5 ± 0.5 5.0± 1.0 6.0 ± 1.0
M6 1.0 5.0 ± 1.0 8.5 ± 1.5 10 ± 2
M8 1.25 11 ± 2 20 ± 4 24 ± 4
M10 1.25 23 ± 4 42 ± 8 53 ± 7
M12 1.25 42 ± 8 80 ± 10 93 ± 12
M14 1.5 70 ± 10 130 ± 20 150 ± 20
M16 1.5 105 ± 15 195 ± 25 230 ± 30
M18 1.5 150 ± 20 290 ± 40 335 ± 45
M20 1.5 210 ± 30 400 ± 60 465 ± 65
M22 1.5 290 ± 40 540 ± 80 630 ± 90
M24 1.5 375 ± 55 705 ± 105 820 ± 120

FLANGE BOLT AND NUT TIGHTENING TORQUE
Thread size Torque N·m
Bolt nominal diameter mm Pitch mm Head mark "4" Head mark "7" Head mark "8"
M6 1.0 5.0 ± 1.0 10 ± 2 12 ± 2
M8 1.25 13 ± 2 24 ± 4 28 ± 5
M10 1.25 26 ± 5 50 ± 5 58 ± 7
M10 1.5 25 ± 4 46 ± 8 55 ± 5
M12 1.25 47 ± 9 93 ± 12 105 ± 15
M12 1.75 43 ± 8 83 ± 12 98 ± 12


jjlink Posted: Fri Apr 27, 2012 10:32 pm

jjlink said:

Can anyone tell me what torque the lug nuts should be tighened to for the mag-wheels? I don't see it in the owners manual...

Click to expand...

For Reference

Chevy Volt:
Wheel Nut Torque 140 Nm, 100 lb ft

NISSAN LEAF:
Wheel nut tightening torque: 80 ft-lb (108 N·m)

FiddlerJohn said:

From the European Tech Manual (M131100030098900ENG):
SERVICE SPECIFICATIONS
TIGHTENING TORQUE
Standard value
Wheel nut N·m 98 ± 10

Click to expand...

John, thanks for that. 98N-m is 72.3ft-lb

BTW, the Gen1 Insight spare measured OD is 20.22" vs. the measured iMiEV's 23.28" OD at 60psi. Pity.

jjlink's previous use of the Gen1 Prius spare sounds better. Off to the junkyard...
http://myimiev.com/forum/viewtopic.php?p=1226#p1226

8 Aug Edit: added jjlink's posting showing the Prius spare mounted on the iMiEV

Joe,

I'm not sure about the ES model with the steel wheels, but with an SE and the alloy wheels you cannot put the same wheel on the front as you can on the rear

I took the wheels off my car to see if the alloy wheels from my Miata could be used on the i and the rear wheel fit just fine. It is a lightweight (9 pounds) 14 by 6 inch BBS wheel with a 195/55-14 tire on it and it's a very close match to the circumference if the i's rear rubber. But, that rim cannot even be put on the front of the car, never mind the dimensions of the wheel or the tire . . . . it physically cannot be bolted to the hub unless some modifications were made. There is a steel collar on my front hub which looks to me like it's only purpose in life is to ensure than nobody can accidently try to put the i's rear wheel on the front

I'm thinking this is one reason why they did not even offer us a spare - The dimensions of the front and rear tires are so different that one spare couldn't be used in both places anyway. My alloy rear wheels are 5 inches wide while the fronts are only 4 inches and the tires are completely different sizes

But . . . . If I need an emergency spare for the rear, I'm in good shape!

Don

Don, thanks for pointing out the hub center diameter front/rear dissimilarity.
I corrected my previous post to credit jjlink for his Gen1Prius spare on the iMiEV and link to his photo showing this.
jjlink: did you try the Gen1Prius spare on the front of the iMiEV also?

The upcoming ]MINICAB MiEV appears to share our drivetrain, and it has 145/12 tires. http://www.mitsubishi-motors.com/en/products/minicab-miev/index.html
A pair of them 12" steelies with low profile 12's could increase off-the-line performance. Assuming the top speed is motor rpm governed, one could keep a 68 mph ability with 165/50R12 tires, or 75 mph with the 145SR12 that is the smallest option on Tire Rack (though a 32 psi max pressure tire with iffy load capacity at 780 lbs)..

Such a setup would give new meaning to Big n Little, because the front spindles look very iffy to accept smaller diameter wheels!

JoeS said:

Don, thanks for pointing out the hub center diameter front/rear dissimilarity.
I corrected my previous post to credit jjlink for his Gen1Prius spare on the iMiEV and link to his photo showing this.
jjlink: did you try the Gen1Prius spare on the front of the iMiEV also?

Click to expand...

I just tried the Gen1Prius spare on the front of the iMiEV and No it does Not fit. It looks like that center ring from the wheel hub is to big to fit the hole in the center of the spare. Also the log holes may be a bit too tight to mount the wheel (I can't tell since the hub is too big).

Thanks, John, appreciate your effort. I need to poke around a junkyard (if there are any left around here) and perhaps latch onto a compact spare and have the center hole machined out...

There are lots of Miata spares on eBay Joe - Here's one for cheap http://www.ebay.com/itm/1990-1998-Mazda-Miata-factory-spare-tire-OEM-original-Very-nice-/170891784384?pt=Motors_Car_Truck_Parts_Accessories&hash=item27c9f1b0c0&vxp=mtr

Pretty sure they'll bolt on the back as they come. I have one in the garage (hasn't been in the trunk of my Miata the entire time I've owned it) so I can measure the circumference of the tire if you need - It's a really 'compact' spare, but having it in the trunk of my car means you can't put much else in there so I've always just carried a patch kit and a mini compressor . . . . which I've never needed in 15 years . . . . thankfully

Don

jjlink said:

I just tried the Gen1Prius spare on the front of the iMiEV and No it does Not fit. It looks like that center ring from the wheel hub is to big to fit the hole in the center of the spare. Also the log holes may be a bit too tight to mount the wheel (I can't tell since the hub is too big).

Click to expand...

I did some more playing around with the wheels today - I might be installing a set of BBS alloys from my Miata on the car, in which case I'd probably have a set of OEM alloys with tires for sale one day in the not too distant future . . . . we'll see

Anyway, the silver center ring on the front hubs is easily removable and without it, the rear wheels will fit on the front. So . . . . for anyone wanting to buy a spare, you could use a 15 inch 4X100mm compact spare from anyone of a dozen Japanese cars and it would fit both the front and the rear of our car if you have previously removed that pesky center ring. It's only purpose in life is to make the rear wheels *not* fit on the front. It's an aluminum ring which is press fit into the front hub. It has a single hole in the lip of it and if you drop a drill bit through that hole and drill a matching hole 180 degrees opposite the original hole, you can then drop a small phillips head screwdriver through both holes and use a larger flat blade screwdriver to pry off the ring - Pry a little on one side, a little on the other side and it will pop off. Replacing it is as simple as tapping it back on with the handle of your screwdriver. I had both rings off my car today testing different wheels and I put them back on when I was done

You could drive the car with 4 of the rear wheels/tires on it, but there's barely enough clearance for the tire to the front plastic inner fender when the steering is turned just so - One size smaller tire would fit nicely. I'm not sure where the speedometer gets it's pulsed information. If it's derived from the engine in the rear, then changing to larger front tires wouldn't change anything, but if it's derived from one of the front wheel's ABS sensors, then an incorrect front tire size would mess up the speedometer reading

I can't for the life of me figure why Mitsu used different sized wheels and tires front to rear on this car - With the ICE version of the smaller bodied Japanese i car, it almost made sense because the engine/trans was in the rear so the front/rear weight bias was heavily shifted to the rear, but with the larger bodied North American EV version with it's heavy battery sitting pretty much equally on all 4 wheels, it would have made sense to me to use 4 wheels/tires of equal size . . . . especially because any car with front disc brakes and rear drums is depending much more on the front rubber for braking

Anyway, there are loads of possibilities for wheels to fit this car, if you are using a suitably sized tire - Many different wheels will bolt to the rear and they'll also fit the front if those rings are done away with

Don

Don, thank you for prying off that cover off the front hub. I had suspected as much, but never got around to removing it. I think that all it does is keep the dirt out of the bearings.

Unlike you, I don't mind the skinny tires. It's my understanding that the unequal tires have to do with proper vehicle balance (understeer/oversteer), and she seems fine to me even when pushed quite hard - I think it would be fun to enter the iMiEV in a gymkhana or autocross. My old Saab 96V4 with its skinny tires used to love the snow.

Anyway, the skinnier the tires the lower the rolling resistance, and that's a parameter I really like to minimize (another reason for running 60psi).

JoeS said:

Don, thank you for prying off that cover off the front hub. I had suspected as much, but never got around to removing it. I think that all it does is keep the dirt out of the bearings

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Nope . . . . all it does is keep you from putting the rear wheels on the front and it was clearly an afterthought or they would have just machined the hub to fit only the front wheels

The front hubs are quite different from any others I've ever seen. The nut holding the bearings and the hubs together and the grease cap which covers everything is on the inside of the hub, not the outside like every other front hub you've probably seen. There is nothing in the center of the 4 studs other than the removable aluminum ring - No way any dirt can get into anything even if you do remove it

I like firm tires too Joe, but when the sidewall says "Max pressure 51 PSI" I gotta believe they put that on there for a reason - If the tire can't flex when you hit a chuckhole, you could break the fibers in the belt of the tire. I run mine at 45 PSI

Don

Thanks, Don, for making the effort to show that other wheels can be made to fit. Is there any other car sold in the U.S. that uses low-rolling-resistance 145/65R15 tires? I'm guessing not which could make finding replacement tires very difficult in the future. So we may need to ability to fit other wheels and other tire sizes in the future.

I did a side-side tire rotation this weekend and confirmed that a 13" 4x100 donut spare from our 1992 Honda Civic (and other 13" rims) fits just fine on the rear drums, but you do need a 15" wheel to clear the front caliper. The shortest street-legal tire i found for a 13" rim is a BF Goodrich 185/55R13, which would reduce circumference by 9.7%. That calculates out to a 74 mph top speed, which would suit me just fine; cause it's gettin there that's the fun part. That extra 10mm of rear width should fit, the main unknown would be just how much of an efficiency hit the performance tires and higher average revs would cause. And they make my moon disc hubcaps in 13" too!

A 14 inch spare (from a Mazda Miata) clears the front calipers just fine, as will most any 14 inch 4 X 100 wheel I'm pretty sure. The rim on my doughnut spare just barely kisses the tab on the front shock where it bolts to the front suspension though. I could make that spare fit by grinding away just a touch of metal there, but I didn't bother, as I'm not really looking for a spare tire to carry around

My 14 X 6 Miata BBS alloy wheels also clear the brakes just fine, but they hit the same spot on the front suspension, but only because they are 6 inches wide. If I elect to use these, I'll cut the wheels and shrink them to be only 5 inches wide and then they'll fit with no modifications at all to the car. '90 to '93 Miatas came stock with 5.5 inch 14's and I'm going to try bolting one of those on the front first, just to see if they clear everything

I was pretty stoked to find that there are appropriate sized 14 inch tires which will give you the same overall circumference as the stock tires and that 14 inch wheels will work . . . . if the rim width and offset are correct

Don

Thanks Don, I forgot you had previously posted about 14's fitting up front. I'm eager to hear if those 90-93 Miata "daisies" fit up front.

Don said:

I was pretty stoked to find that there are appropriate sized 14 inch tires which will give you the same overall circumference as the stock tires and that 14 inch wheels will work . . . . if the rim width and offset are correct

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The experience that Honda Insight owners have had trying to find an alternate tire that matches the fuel efficiency of the OEM tire has shown how important low rolling resistance and weight are. Even with alternate wheels identified, the challenge would be to find light, low-rolling-resistance tires in sizes that would result in circumferences similar to the OEM tires. Unlike tires sold in the E.U., tires sold in North American don't have any information about their rolling resistance, and tire weights aren't always easy to find.

Mounting tires with higher rolling resistance and weight than the OEM tires will reduce the range which is already marginal for some people. The reduced ranges being reported by those living in cold climates is likely partially due to heavy, high-rolling-resistance snow tires that they're using.