Tyres

My 2006 Nissan Pathfinder turbo diesel STL Auto has only done 80,000 km and it has been through three sets of tyres and four sets of brakes, and the costs keep mounting. Last week I rang my dealer to book it in for the 80,000 km service and was astounded when quoted $1500. They said if I don't do the service there I would jeopardize my warranty, and there are things that have to be fixed on it. Is this a fair price, I think it is unreasonable? I would never buy another Nissan again, particularly when Toyota offers fixed price servicing.

The tyres on my 2008 VW Jetta FSI manual are scalloped. After asking for them to be rotated at the 30,000 km service because of wear I noticed they were noisy. The dealer told me to drive a few thousand kays and they would bed in, but they didn?t. The next time I reported the noise I was told the front tyres had developed scallops on the inner edges. The suspension checked out ok. The service manager stated that it was common for the tyres on the Golf, Jetta, Passat to show this type of wear at this mileage and that it was viewed as general wear and tear. VW do not warrant the tyres, and will not replace under warranty, but I don?t think it?s fair. What would you suggest I do?

The driveline on my 2004 VW Touareg R5 TDI has just been changed after excessive thumping problems restricting us to travel at a max of 25 km/h. Before the service, the car had chewed its way through two sets of Cooper tyres even though it has only done 35,000 km. Would the driveline change increase the tyre life and make it more economical?

Could you please tell me the recommended tyre pressure for my 2010 Toyota Prado GXL?

Recently I noticed that the tyres on my 2000 VT Holden Commodore are worn out from the inside. I can understand the front ones may be due to a wheel alignment issue, but I don?t understand why the rear ones are also worn out. I purchased the car when it had 65,000 km on it and the tyres were near new at that time and it?s now done 100,000 km. Is there some issue with the rear wheel?

Does the DSC have to be recalibrated when you replace tyres on an AWD Territory?

Testing this week by the NRMA and the Daily Telegraph has shown that just changing to a different profile tyre can increase your speed by up to 8 per cent without you being aware. By law all speedos have to be set to read higher than your actual car speed to allow for margins of error. The actual margin varies between car makers and models and is not disclosed.The testing found that one car's speedo read 50km/h  but its actual speed increased from 44km/h to 48km/h just by changing the tyres. Similiar increases were achieved as the car went faster.The NRMA says the tests show that if you alter your car from standard you could be unknowingly travelling over the speed limit."If a vehicle as produced by the manufacturer has a speedometer calibration margin near zero (ie the speedo is very close to accurate) an 8 per cent change due to larger wheels and or tyres could easily mean the driver would be travelling at a higher speed than indicated by their speedometer. If they are very close and you change your wheels and tyres you'd be well over" said NRMA vehicle safety expert and senior policy adviser Jack Haley.The NRMA and the Daily Telegraph undertook testing over two days at Sydney's Eastern Creek raceway this week using four popular cars; a commuter sedan (Toyota Corolla), a sports car (Honda Civic Type R), a family car (Subaru Outback) and a large 4WD (Toyota Hilux).The tests compared the cars' actual speed to the speedo reading plus how the speed was effected by altering tyre pressures and changing to a different profile tyre.The results found that none of the cars travelled at the same speed as their speedos were showing under any circumstance.On average they were about 3km/h slower than the speedo reading and that increased up to 6km/h slower at the top speed checked 120km/h. None of the cars went faster than their speedo was showing but Mr Haley said that could occur depending on the car and the level of modifications.The tests also found that speeds do not alter much if your tyres lose some pressure."Varying tyre pressure does not affect speedo accuracy significantly. The largest difference was 2.8 per cent" Hayley said.He said that with the introduction of mobile speed cameras motorists should not rely on their speedo reading if they altered their car from standard."Motorists should be very careful if fitting optional or accessory wheels and tyres."Subaru spokesman David Rowley said "any change to non-specified tyres can have an effect. We recommend that owners stick to the tyres specified by the manufacturer."

Could I replace the expensive 245/45/17 tyres on my FG Falcon XR6 with 235/45/17 as have been fitted to all other XR6 models? The tyre width is only slightly smaller by 10 mm, and the difference in rolling diameter is only about 9 mm. I am a mature driver and drive carefully.

I recently had to replace a punctured tyre, and when I did the tyre place told me I should replace all four tyres. If I didn't, they said, I could have serious problems. Is this correct?

Is it safe to replace 215/65 R16 tyres on a Hyundai Tucson with 215/60 R16 tyres? If so, what are pros and cons of doing this?