Going to smaller wheels MPG worth it?

[Carburettor]

I currently have some 20 x 9j wheels on the van which came with it when I bought it. I’m looking to move down to 18 x8j. Will this make a difference to MPG or does it need be a smaller wheel than 18x 8? I know these are still inside the standard wheels size that came with the T6.

It’s quite a lot of admin and hassle to change wheels and tires. But before the 20 inch wheels need new tire tires, I thought this would be a worthwhile change.

So is it worth it even at 18 x 8j, or should I go smaller or stay with the 20s..

 

[dubber36]

It's more to do with the weight of the wheels and tyres, therefore the rotational mass than the size that affects fuel consumption.

 

[StratosFearXX]

I've just gone from 265/40/20 8.5j and 10j staggered to 235/55/18 8.5j all round. I think I'm getting better mpg but haven't done a longish trip on 'em yet.

 

[Martin Stockwell]

18s look quite small and silly, but not as silly as 17s, 20s are to big IMO with the available tyres in order to fit in the arches without scraping, and becomes expensive. I found the best option was 19s, keep the looks but the tyres are easier and cheaper to get.

 

[Carburettor]

18s look quite small and silly, but not as silly as 17s, 20s are to big IMO with the available tyres in order to fit in the arches without scraping, and becomes expensive. I found the best option was 19s, keep the looks but the tyres are easier and cheaper to get.

I was looking at some steels that have a bit more poke but still are 18x8. How do the 19s perform?

 

[Martin Stockwell]

navis do some nice 19inch steels. i get on average 35-40mpg, its a BiTurbo 204, LWB T32 with a caravelle and camper conversion, so it isnt light.

 

[nayfie]

Martin, what tyre width are you running?

I've been reading this thread with interest, as my 19"s are running 275 all round. I'm averaging around 32 MPG on my 150 BHP T32 SWB with no weight in it. I rarely get past 34 MPG despite trying to drive sedately.

The 275 on the front I feel are a tad wide, they poke out a slightly especially when cornering, and so that can't be good for aerodynamics. Though personally I do like the look of them.

But to echo what you say, I do think 19" are the sweet spot in terms of size, tyres profile, and versatility.

 

[Skyliner33]

People seem to forget, when factoring in mpg, that the reading from the DIS will be affected by the tyre diameter. So changing to a smaller tyre diameter will make the mpg go up on the display (more than it actually does).

 

[Carburettor]

With 20s and 245/45/20 i calculate 6% difference, so mileage and mpg on the DNS are 6% out. But there’s going to be actual difference in MPG too. Which is what iIm asking about. I’ve read people see a difference in about 5mpg, id expected that when I drove on motorway at <70, 150hp Kombi with slidepod, minimal weight, decent pop roof that’s low drag.

So back to my original question is the ACTUAL change in mpg worth it dropping to 18x8j? Looks aside (19’s seems pointless as it’s already bigger than standard and so will be more drag and resistance so may as well keep the 20s) and I like the look of 18 steels on a van, personally.

20s are for sale btw - SuperMetal Cell matte black

 

[temporarysecretary]

I currently have some 20 x 9j wheels on the van which came with it when I bought it. I’m looking to move down to 18 x8j. Will this make a difference to MPG or does it need be a smaller wheel than 18x 8? I know these are still inside the standard wheels size that came with the T6.

It’s quite a lot of admin and hassle to change wheels and tires. But before the 20 inch wheels need new tire tires, I thought this would be a worthwhile change.

So is it worth it even at 18 x 8j, or should I go smaller or stay with the 20s..

As Skyliner says the diameter introduces inaccurate data to the speedo. On 20s (depending on tyre profile) you are covering 10% more distance than the van thinks.

100,000 miles on the odometer means the can has done 110k.

30MPG = 33MPG

So it might not be as bad as you think.

I wish my van did more MPG however every van I have ever driven (mostly work vans with stuff in and small steel wheels) average about 30. So its either me or that's just what heavy slab shaped 3 tonne bricks do.

 

[Martin Stockwell]

Martin, what tyre width are you running?

I've been reading this thread with interest, as my 19"s are running 275 all round. I'm averaging around 32 MPG on my 150 BHP T32 SWB with no weight in it. I rarely get past 34 MPG despite trying to drive sedately.

The 275 on the front I feel are a tad wide, they poke out a slightly especially when cornering, and so that can't be good for aerodynamics. Though personally I do like the look of them.

But to echo what you say, I do think 19" are the sweet spot in terms of size, tyres profile, and versatility.

I run 19x8.5 35et on the front, and 19x9.5 40et on the rear. Tyres are 245x45 front and 265x45 rear. I run my van pretty low as I'm on air, and I have no rubbing issues. it took a lot of measuring and testing to get this setup right so i know what does and doesn't work. i in effect have the perfect setup that takes in to effect looks, comfort as well as cost and longevity of tyres.

 

[Sasquatch]

My 110 regularly gives me into the 40s onn18s with 235/55 rubber. Some of that will be a skillful (if I say so meself) and sympathetic right foot, but I wouldn't be able to do it if the van wasn't capable.

Looks fine on 18s, the tyres fill the arches ok at 55 without raising the gearing intolerably. In any case, no one buys a van for the way it looks.

 

[Martin Stockwell]

MPG - most peoples issues regarding mpg isn't to do with tyre size, although jumping up to 20s can make a significant difference, dur to rolling mass, and width adding on additional rolling road resistance, but we are only talking maybe 1 or 2 mpg. something which people fail to get done is having adjustable rear bushes fitted, especially with any suspension modifications. with the vans lowered, or raised, even a small amount will drastically cause the wheels to toe in (or out if raised). this can make 5+ mpg difference. we tested this on a bog standard van, brand new. drove it for 2months on standard suspension, same wheels, then 2 months lowered, then 2 months with added adjustable rear bushes. 8mpg difference it made having the rear bushes installed. and we noticed significant reduction in tyre wear as well....

 

[Sasquatch]

Fortunately mine is neither lowered nor raised, so that factor can be eliminated from my MPG efforts.

 

[Martin Stockwell]

Fortunately mine is neither lowered nor raised, so that factor can be eliminated from my MPG efforts.

and that's why your getting 40mpg, most people on here have some kind of wheel or suspension modification to improve the looks or drivability, or functionality. but this messes with the factory wheel alignment that most people only think about having the front wheels adjusted!

I had air ride fitted for multiple reasons, one to make it no longer look like it was on stilts. self levelling when i move the caravelle seat configuration about, or add a trailer, ability to air out to make it easier for my grandad and the kids to get in and out. and i can independently adjust each corner to level it when we go camping.

if its done right you'll know, even loaded up with a poptop, caravelle configuration, 7 people, lpg, airride etc etc etc, i still get close to 40 on a run, and 30-35 toeing a trailer full of camping gear when we go away. i can guarantee over 75% of people if not more when they have added non factory size wheels or modified suspension have not had rear adjustable bushes installed!

 

[dubber36]

Let's say smaller wheels will gain you 3-4 mpg. There will be a cost involved in changing wheels and tyres, even if you sell the 20's and will need new tyres anyway. How long will the payback in fuel saving on the initial outlay be?

 

[Sasquatch]

im a big fan of functionality. That's why I left it alone!

 

[Carburettor]

Powerflex Poly Bushes - Adjustable - Set Of 4 | Transporter HQ VW Transporter T5/T6 - Powerflex - Rear Wishbone Bushes - Adjustable - Set Of 4

Okay, more reading required. JK sell 2 kits, one for £120 & the other £150, they use the same parts picture but this kit is for both the bushes in the rear arm (both kits).

Need to find out what is required, I assume both kits would be to get the benefit of the adjustment?

 

[Martin Stockwell]

Powerflex Poly Bushes - Adjustable - Set Of 4 | Transporter HQ VW Transporter T5/T6 - Powerflex - Rear Wishbone Bushes - Adjustable - Set Of 4

Okay, more reading required. JK sell 2 kits, one for £120 & the other £150, they use the same parts picture but this kit is for both the bushes in the rear arm (both kits).

Need to find out what is required, I assume both kits would be to get the benefit of the adjustment?

Yes you want upper and lower, and you want the powerflex kit.

 

[Bav]

...no one buys a van for the way it looks.