The weight of wheels, rims, and tyres

Ratbag

Ratbag

Administrator
Joined
Jan 1, 2012
Messages
7,474
Location
Bayside, Melbourne, Vic
Car Year
MY06, MY10
Car Model
Forester SG & SH
Transmission
5MT/DR & 4EAT Sports
I fitted the brand new spare on SWMBO's SH today, as the front P/S tyre is unroadworthy. Seems to me the alignment of at least the front is cactus.

The other 3 tyres still have about 4.2 mm (total) tread left (35%+ of the safe tread!). The new tyre has exactly 8 mm tread depth. The difference in rolling circumference is less than 2%, so should be fine on the front with the open diff.

Seems to me that these are the original tyres - at 85,000 kms!! The batch number is identical on all five tyres.

Anyway, the point is that I weighed the brand new rim and tyre (never been on the car; not once). It weighed 21 kgs! All I could do to lift it in and out and fit it! This is an OEM alloy rim and G95.

I have the weight of my SG rim, and rim + tyre written down somewhere, so will add this later.

It's a lot heavier than the 215/60 16" OEM alloys on my SG.
 
Hi RB,
A tyre dealer years ago said it was common for the left hand front (passenger) tyre to wear more than the right hand front tyre because of the weight transfer that occurs when you negotiate roundabouts.
Presume on left hand drive cars it will be the opposite.
 
^I found the same on front wheel drive vehicles even before roundabouts in NSW.

Ratbag said:
It weighed 21 kgs! All I could do to lift it in and out and fit it! .
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You should have a go at changing the wheels with muddies on my Triton!
 
Wow, thats actually heavier than my 225/70R15 with audi rim. They came in at about 18-19 on the scale from memory.
 
havachat said:
Hi RB,
A tyre dealer years ago said it was common for the left hand front (passenger) tyre to wear more than the right hand front tyre because of the weight transfer that occurs when you negotiate roundabouts.
Presume on left hand drive cars it will be the opposite.
Click to expand...

also the typical camber in the road has you steering slightly right most of the time.

Whiteline even offers an asymmetric caster kit to compensate for this.
 
2013 H6 OB, 17" wheels:

Stock wheel is quite light at 21.7 lb and stock tire at 24 lb, total: 21 kg
Stock wheel and normal AT tire: 22+31=53 lb total: 24 kg
Stock wheel and BFG three ply sidewall TA KO2: 22+39 lb total: 27.5 kg

Off-road rally wheel and BFG TA KO2 = 24-25+39 total: 29 kg

Basic steel wheel and BFG 31+39=70 lb total: 32kg

At what point would one be damaging the drive-line with all that added weight? Or would brakes be the only worry?

One can have a 21 kg vs. 32 kg difference per corner!!!

Good luck getting strong lightweight off-road wheels unless cash is burning holes through your pockets.

Perhaps one can manage with a Braid Fullrace A, which is 17lb and relatively strong but still quite below OEM load rating.
 
My 16" Speedlines are 9kg each.
plus whatever the 215/70 BFG AT KO's weigh.
 
My OEM 16" rims on Roo2 weigh around 8.2 kgs each (bare, IIRC ... ) vs around 11.x for the bare steel rims.

Anyway, I had the wheel alignment checked on RonnyRoo this morning. Not unlike Roo2, the alignment was within spec on each wheel, but all pointing in slightly different directions.

RR now drives completely differently. Less barge-like and more like Roo2 :biggrin:.

$58 well spent for a 4 wheel alignment.
 
Gidday ST

stilson said:
Seems like someone's been neglecting wheel rotations.
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Possibly, but three wheels were going in more or less the same direction, while the front P/S wheel was going in another ...
 
IIRC the new 215/55 17 tyre and stock 17" rim on my 07 XT weighed 19.5kg on our rather expensive digital bathroom scales. The 205/55 16 tyre and alloy rim on our Golf was 18kg. And I could certainly feel the difference when hanging onto one of each at the same time. I'm still wondering if I've permanently stretched my arms! :lol:

Also Subaru claim a 07 Forester X manual weighs 1395kg while the XS with alloy wheels is 15kg less at 1380kg. Most, if not all of that, must be in the lighter alloy wheels. Usually the better equipped cars in a model range weigh more because of more equipment although in the case of the 07 Forester I can't think of anything extra that could add more weight to an XS other than the sunroof on the Luxury version.
 
RB, sounds like a combination of minor alignment specs adding up, plus other factors like roundabouts etc. I'm surprised it had such a big impact on one tyre & not the others though

MiddleAgeSubie said:
2013 H6 OB, 17" wheels:

Stock wheel is quite light at 21.7 lb and stock tire at 24 lb, total: 21 kg
Stock wheel and normal AT tire: 22+31=53 lb total: 24 kg
Stock wheel and BFG three ply sidewall TA KO2: 22+39 lb total: 27.5 kg

Off-road rally wheel and BFG TA KO2 = 24-25+39 total: 29 kg

Basic steel wheel and BFG 31+39=70 lb total: 32kg

At what point would one be damaging the drive-line with all that added weight? Or would brakes be the only worry?
Click to expand...

Thats a nice compilation lol. Certainly a big variation! :O

The extra weight would also have a bearing on the bearings - sorry, had to say it :rolleyes: as well as brakes & suspension. A big impact on economy.
 
NachaLuva said:
The extra weight would also have a bearing on the bearings - sorry, had to say it :rolleyes: as well as brakes & suspension. A big impact on economy.
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Thanks for that. My numbers are just that, numbers. I am running normal AT tires on stock wheels for now, which means the weight gain only affects performance a bit. I would not like to put very heavy tires on very heavy wheels.

At what point would the extra weight start taking a toll on bearings/suspension?

20% over stock? 30%? 50%?

People like taza seem to be running heavy combos without issues.

What I want would be 62 lb vs. 46 lb for stock.

There is no way to reduce the wheel weight without running into load rating concerns (or spending astronomical amounts of cash). I could get light BRAID Fullrace A wheels but they would still only be half way between the minimum allowable load rating and the OEM load rating thus causing a bit of concern when driving fully loaded over rough roads.
 
taza said:
My 215/75r15 BFG's on stock SF steel rims weigh around 30kg
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Damn! Thats heavy!! My LT Kuhmo muddies, same size, on Audi rims are 22kg :eek:

MiddleAgeSubie said:
At what point would the extra weight start taking a toll on bearings/suspension?
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Haha, yeah. No real way to answer that without going into the load rating of the bearings, working out moments of inertia, angles, etc.

I do know that only a couple of weeks after I put my muddies on for a hard day on the tracks that a wheel bearing gave out in spectacular fsashion on the freeway in heavy traffic! :eek::huh:

They were obviously on their way out and the extra load of that day was too much for them.

Logic dictates that the greater the unsprung weight, the greater the load on the associated components, but who knows at what point & how much :shrug:
 
stilson said:
Coincidence Nacha.

Wheel weight has negligible effect on bearing load. Wheel offset is the killer.
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Good to know. So, at what point does offset become an issue?

Say, mine is 48. What if I want 42? How about 38?
 
MiddleAgeSubie said:
So, at what point does offset become an issue? Say, mine is 48. What if I want 42? How about 38?
Click to expand...
There aren't any hard and fast numbers. The ex-factory offset attempts to place the static load mid-way between the two bearings, so it's all symmetrically loaded. Change of offset simply adds more static to one bearing and less on the other - lower offset, more static on outer - and this amounts to higher roller/race pressure and hence wear prospects. Bearing failure results in fairly short order when the surface hardening is penetrated, so there's no easy way to determine life expectancy from a particular decrease (or increase) in offset.
 
Basically, factory offset = fine. Remember offset effect is dependant on wheel rim width!!!!
 
Venom said:
Basically, factory offset = fine. Remember offset effect is dependant on wheel rim width!!!!
Click to expand...
I'm not sure how you arrived at that conclusion. You can do simple calculations. In principle the standard offset for an OEM wheel places the centreline of the wheel over the mid-point between the two hub bearings. It represents how far out the wheel-mounting face of the hub is beyond that mid-point. Regardless of wheel width, that same offset spec will similarly locate the mid-plane of a wheel in that same "correct" location.
 
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