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Tyres and Tyre Pressures


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Hello. 

I am a new Alphard owner. Mine is a 2006 3.0 V6. 

It is fitted with Japanese Trafficstar wheels which have non standard tyres. The tyres are 245/40ZR19 98Y. Can anyone please tell me the correct tyre pressure, front and rear, for this tyre on this vehicle. 

Thank you. 

IMG_20220621_141103515_HDR.jpg

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Hi Nick C,

I recall seeing a post on this forum stating 38-40psi generally, and our campervan converter suggested 38psi both front & rear for 225/55R17 tyres. So, you could ask whoever did the campervan conversion (perhaps the simplest solution). Alternatively, it might involve quite a bit of sleuthing & emailing....  

These were the weight figures on the Japanese import certificate (Gen 1 2005-07):

Weight 

Total

Front

Rear

 

(kgs)

 

 

 

 

 

 

Car: Net

1870

1070

800

 

 

 

 

Car: Revenue (i.e. GVW)

2255

 

 

So there's a difference of 385kg between unladen and laden weight (which doesn't seem a lot for a 7/8 seater...) for the base Alphard, but there was no breakdown in the figures for front and rear separately when laden. When converted, there's the added unladen weight from permanent campervan furniture, but not 5-6 people in the back when laden. After messing about on a weighbridge several times, putting the whole vehicle on then the rear only (and subtracting the difference), we worked out the unladen and laden weights for each axle on our campervan. Divide the axle weight by 2 to get a load for each tyre...

Tyres are weight (and speed) rated, so your 98Y can each carry 750kg maximum (1500kg for the axle overall). So far so good, but the recommended Alphard tyre pressures in the manual (34psi or 2.3kg/cm2) are for the base vehicle rather than a campervan and ultimately it depends on your specific max weight (front & rear), also the tyre type/manufacturer.

For our campervan, Continental, Falken, Kumho and Nokian responded to e-mail enquiries, but to get them to offer figures we needed to point out that the conversion meant that standard Toyota figures didn't apply, and choose a specific tyre first to ask them about, rather than making a general enquiry. In the end we went with Falken front (101 load rating) & Nokian van tyres rear (109/107 rating), which the manufacturers said should be 34 & 41psi respectively, but this was based upon our specific weighbridge figures which showed that, when laden, the extra weight primarily loaded on the rear axle (gear & bikes on towbar etc...) and made no substantial difference to the front end. Of course this is just an example to show that tyre pressures may need to be different front and rear - your situation may be different....

Of course this can all involve a lot of work, so asking whoever did the campervan conversion might be the simplest solution....

Regards,

pcous


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