Compatible wheels

**ozgti** · 24-05-2018, 10:50 AM

Neither is lowering more than 25mm, blow off valves and removing removable seats out of a multivan...

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**Kiels3927** · 24-05-2018, 02:54 PM

Back from the run up to Townsville, the first long run since I fitted the Amarok 18s & Bridgestones. A few points:

The ride is way softer than I was getting with the 16" Michelins & way less flighty. The car needs litle input to stay straight & turns more positively. Having a newfound fear of potholes with the shorter sidewalls, I was more vigilant driving, but survived one or two bumps OK. On the other hand, the bridge between Ayr & Home Hill can still destroy your your sex life and would test a hovercraft.

I could not discern a difference between speedo indication & GPS reading compared to the 16s. 100 came up on an indicated 103something & 110 at a maybe 114. I did try to sanity check the odometer against the 10 km road signs, but that quadrant of the screen is a bugger to read unless the sun is just right over the left shoulder so my sampling was less than desirable. However, if MRD has their spacings close to right, then 10 km roadsign equates to 9.75-9.8 odometer, the exact opposite of what I would have expected from the speedo readout. That being the case, it makes calculating economy a tad imprecise, though an extra 2 km per hundred won't mean all that much.

I'll wait until I pass that speedo check on the Toowoomba road to resolve that issue.

Speaking of economy, I used about ½+ litre per hundred more this time to & from Townsville than I did the same time last year. Sure there was more road works this time about, particularly with queuing behind lights & significant 40 kmh stretches accordingly, but I hope that the wider rubber didn't cause the difference - or the box & engine reset after the last service's oil change. Interestingly, it still is about 1 liter per hundred higher usage coming back from north than the run up, an issue I've found every time on this run, just as the Newell bleeds me more petrol heading north than south, It would be interesting to check the topography. It must have lazy climbs in one direction & tough ones the other.

The biggest nuisance I experienced was when the fuel warning went off far earlier than I expected on the way back, albeit the needle was on the first red tick. When I tanked up 50 km later, it only took 72 litres, suggesting that it went off when there was 67-8 litres left in the tank, somewhat prematurely, I would have thought, and no, I was running on the flat when it happened, not on an uphill run & the light stayed on until I filled up.

Wheel arch clearance was generally OK. In fact, I think I touched the left on a hard, hard RH maneuver at a trucky stop meal break. I must get around to sticking my head in & checking.

**Sunny43.5** · 30-05-2018, 11:24 PM

Quote "It would be interesting to check the topography. It must have lazy climbs in one direction & tough ones the other. " Here in South east Qld that is the case , we go Moto cross riding at a park just over the top of Cunninghams Gap . With the van and trailer its a long slog from the eastern side as you are climbing continuously for around 8 kays with reduced speed limits all the way up it is a hard pull. But when we come home the run up to the top from the western side is very short only around 1.5 kms and it is very flatish as the topography from that side is very gradual . Same for the Toowoomba range crossing .

**Kiels3927** · 12-06-2018, 08:51 PM

OK, I've just done another 1200km run to Raglan & back and the economy was 9.2 on the first tank & 9.5 on the second (half) tank. my economy has gone from bad to worse compared immediately after it was given a gearbox flush out and refill 30,000 k ago. Then, I was getting 7.5-8.5 on the long runs, the first score being for the 650k leg Brisbane to Rockhampton & that now compares with the 9.2 last Thursday.

What's different? Haven't I reeducated the gearbox properly after the most recent service & reset, or are the wider 18" tyres causing that much extra drag? Is there any significance that it's taking an extra half a second or so for the motor to fire up these days?

**Umai Naa!!** · 12-06-2018, 09:09 PM

Is the new wheel and tyre set heavier than the old one?

How about the pressures and the alignment?

Gearbox won't take much driving to figure out what your good/bad habits are.

Extended cranking might be due to a sad battery.

**Kiels3927** · 12-06-2018, 09:54 PM

Is the new wheel and tyre set heavier than the old one?

I imagine so, but I wouldn't have expected that to cause a 20% fuel increase

How about the pressures and the alignment?

Pressures as per VW recommendation checked the day of each trip. Alignment done when new tyres were fitted.

Gearbox won't take much driving to figure out what your good/bad habits are.

.. and they're its habits. I drive generally on cruise control on long runs.

I guess that I could reset the gearbox when I clear the traffic on a trip & see if that helps.

Extended cranking might be due to a sad battery.

Battery was deep charged shortly before trip & is holding charge OK. I do that charge routine every 3-4 months on recommendation.

**Sunny43.5** · 12-06-2018, 10:06 PM

I spent some time doing a Google search about pros and cons of larger diameter rims and also fuel economy pros and cons , Seems that the larger rims increase rolling resistance resulting in higher fuel consumption due to some technical reasons beyond my feeble brain . But even the extra weight of the bigger rims will cause an increase in consumption , from many pages it seems that car makers use complex calculations to get the best economy and performance from their engines using certain sizes to match those engines . Once you change those recomended sizes your economy and performance goes out the window .

**Kiels3927** · 13-06-2018, 08:27 AM

Then live with it I must.

**Kiels3927** · 19-07-2018, 05:27 PM

Did a weekend in the Granite Belt the weekend before last, which included an odometer check over 5 kays on the way up. Turns out it is accurate within a handful of meters, assuming the MRD got their distances right. That's nice to know.

In the way up, the trip computer reckoned I'd achieved 7.2 km/100, which based on experience of a full tank prediction would have been something around 8 +-. The run home was another thing again. I tangled with traffic running (walking) in the range of 70-85 kmh from Warwick to the Ipswich Motorway & my overall economy when I tanked up again next day was 9.2. That squirt, coast, brake, squirt driving sure screws up the wallet.