Tyres to increase ground clearance

[Greg&Mel Australian Cali]

I wish to increase the ground clearance on my T6.1 4Motion Cali. This will be very useful when negotiating rough tracks and driving on beaches in Australia.
It will cost approx. $10,000 AUD to add 27mm by a suspension upgrade.
But at no additional cost you could gain 11 mm of additional clearance when buying new tyres by increasing the tyre size and changing from 215/60/17 to 215/65/17, with the added benefit of a softer ride.
This will change the indicated speed on your speedo, but as speedos generally indicate an approximate 3% slower speed than you are travelling then the 3% added to the circumference of the tyre makes it more accurate.
So the questions then are, will the larger size fit and not rub within the wheel bay, and will the slightly larger spare tyre fit within the spare carrier space? Also, what impact on fuel economy?
Has anyone tried this?
Greg

 

[sidepod]

I'd have thought the question was more "11mm? WTAF?"

 

[Alan Andrews]

There was an article on here the other day for air suspension. I'd have thought this will be a better option.

 

[B J G]

I have 235/60/17 tyres on and they give no probs on clearance. Speedo is OK.

the 235/60/17 comes up as having 12mm more sidewall than a 215/60/17. 215/65/17 has 10mm more.

The 235 would be a better option for sand due to the extra width.

225/60/17 103 is another option that gives a slight height increase of 5mm

Front wheel arch outer edge is the area that is closest to the wheel/tyres, rear doesn't tend to be a problem.

 

[Greg&Mel Australian Cali]

So the verdict, as I understand from ‘researching’ the web, is that 225/65R17 will fit a Cali and will not rub with standard suspension. It will also fit in the spare wheel carrier.
235/65R17 are good if you have raised your suspension - and it can be squeezed into the spare wheel carrier.
The 235/65 tyre will increase the circumference by 4.8% and presumably lead to an apparent increase in fuel use as a result. I say ‘apparent’ because the Cali computer works this out and a larger tyre diameter interferes with the calculation. Is there anyone out there who has worked out their real world fuel economy after making a tyre size change? Or is a maths Professor?
Of course, your speed will be higher at the same revs but most car Speedo’s indicate 3% faster than your real speed. So I wouldn’t worry about that.
Some people comment that handling will suffer with higher sidewalk tyres. My view is that I wouldn’t have bought a Cali if race car handling was high on my priority list. Comfort would certainly improve and that is a high priority for me.
Any takers on the fuel economy question?

 

[B J G]

Not done fuel consumption check in detail since going to 235/60/17 but>
Distance trip now approx 10% under Google and SatNav route info.
Fuel consumption on display shows approx 5% drop but if the 10% distance is factored in it seems no worse or better.
Traffic has been congested on recent trips making a direct comparison difficult.

This tyre change also done at the same time as DSG reprogrammed. It now only uses 7th gear at over 60mph.

 

[Greg&Mel Australian Cali]

Thanks BJG,
That is what I thought, that though the fuel economy indicated by the Cali computer would change by 4 or 5 % that the real fuel consumption would not be significantly affected.
I will drive my new Cali until I need new tyres and then change from the 215/60r17 to 225/65r17, or perhaps larger if I think they won’t rub.
The extra bit of clearance is very useful in Australia for driving on outback roads and beaches.

 

[HugoFar]

Seikel have a good page that gives some limits for what tyre size, ratios etc are compatible. Worth a look.

https://www.seikel.de/wp-content/uploads/2018/06/EN_T5-T6_ground_clearance_2016-07.pdf

 

[HugoFar]

Here's another link that may be helpful.

215/60-R17 vs 225/65-R17 Tire Comparison - Tire Size Calculator | Tacoma World

225/65-R17 tires are 1.36 inches (34.5 mm) larger in diameter than 215/60-R17 tires and the speedometer difference is 4.8%

www.tacomaworld.com

I've used this one a few times over the years for different tyre combos.

 

[The Tall Luthier]

Another ancillary benefit is that your mileage will report 4.8% lower. On a reading of 100,000k you’ll have actually travelled 104,800k

 

[Velma's Dad]

I've never looked much at T5/6 suspensions but wouldn't a set of spring spacers be all that's needed? Am I missing something?

Alternatively/as well (and apols for going slightly off the OP's specific question), on rough tracks ride height is only one side of the story - look as well at protecting the vitals. I don't know what bits of a T5/6 are vulnerable but on most vehicles it's sump, wishbones, steering arms and exhaust. I'm sure there are proprietary shield kits available for Transporters, especially in Australia.

 

[B J G]

Thanks BJG,
That is what I thought, that though the fuel economy indicated by the Cali computer would change by 4 or 5 % that the real fuel consumption would not be significantly affected.
I will drive my new Cali until I need new tyres and then change from the 215/60r17 to 225/65r17, or perhaps larger if I think they won’t rub.
The extra bit of clearance is very useful in Australia for driving on outback roads and beaches.

I had some scuff marks on the rear inner arches which I resolved with a hot air gun and reshaping the plastic liner. That was due to having air suspension and on lower setting.
I have read of others using the same method on the front liners, mainly when fitting big and wide wheels.