# Hymer s660 - looking for larger tyres or wheels for cruising rpm Drop



## BrightonRider (Apr 2, 2017)

Hi,

Hoping someone can help me.

Looking to drop the rom when cruising in our 1993 hymer s660 (merc 410d) with a 2.9 NA diesel Mercedes engine. The easiest route is to increase the rolling circumference by upping wheel/tyre size.

I currently have stock 14" wheels/tyres. I have 2 queries:

1) What is the largest 14" tyre that will fit without rubbing?
2) what 16" wheel options do I have. I know Mercedes 609 wheels fit but these are hard to source. What else? Do these later sprinter wheels fit? 16"MERCEDES SPRINTER/ VW CRAFTER TWIN WHEEL (2006-PRESENT) 195 75 16C TYRE 6mm | eBay


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## listerdiesel (Apr 3, 2017)

I'm pretty sure that sprinter running gear is not compatible with the 6XX series, happy to be proved wrong though.

Our 614D has 16" rims with 215 section tyres which we have uprated to 225's.

As the 614 and 814 use the same body, and the 814 uses 17.4" rims, there's possibly more wheelarch room on the later vans than your chassis.

Peter


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## BrightonRider (Apr 3, 2017)

Hi Peter,

I know that the 6xx 16 wheels fit with 205R16 tyres on our van as it has been done a lot. I'd like to know is if the later merc sprinter model wheels fit as they are relatively easy to get hold of compared to 6xx wheels. The 7xx wheels offset is meant to not be compatible with my van.

I can't find the offset for my 410 platform to compare. Any one know it?


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## listerdiesel (Apr 4, 2017)

Give me some VIN numbers and I'll look it up in the EPC parts system and see what it says.

The 6XX and 8XX hubs have the discs internal to the hubs, ie the hub has to come off before the disc can be removed, while I believe that the Sprinter discs are external to the hub like on most cars.

Peter


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## Byronic (Apr 4, 2017)

The 709d tyre size 225/75R16N Wheel Rim 6JX16H2 Part No. 6684000002 

The 609d tyre size 215/75R16N Wheel Rim 6JX16H2 Part No. 6694000002

The only difference seems to be the Part No. So it appears you're not limited to just the 609d if looking for replacement wheels, the offset should be (see below) the same on the 709d.

Buuuuut the info. above is from 2 sources ie the 709d is from my MB original sales brochure and the 609d from a basic generic workshop T2 manual. The manual could be inaccurate, mind you, as could be the brochure, MB make plenty of mistakes.

Upping from 14" to 16" should give you a 13% to !4% decrease in revs. Say a 400 rpm decrease to 2600 if you're cruising at 3000 rpm at the moment, norra lot!


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## BrightonRider (Apr 4, 2017)

listerdiesel said:


> Give me some VIN numbers and I'll look it up in the EPC parts system and see what it says.
> 
> The 6XX and 8XX hubs have the discs internal to the hubs, ie the hub has to come off before the disc can be removed, while I believe that the Sprinter discs are external to the hub like on most cars.
> 
> Peter



Hi Peter,

Thank you for the offer. I have emailed you my vin number.


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## BrightonRider (Apr 4, 2017)

Byronic said:


> The 709d tyre size 215/75R16N Wheel Rim 6JX16H2 Part No. 668400002
> 
> The 609d tyre size 225/75R16N Wheel Rim 6JX16H2 Part No. 669400002
> 
> ...



Another 410d owner tried some 709d wheels with 205 width tyres and they fouled on the leaf springs. But the 609 fit perfectly. 

This thread talks about sprinter wheels fitting:

1994 T1 410d Gearing improvement. - Mercedes-Benz Owners' Forums

He used earlier wheels (2007) than the ones I have access too (2014). Is there any difference?

I've done a tyre calculator and it shows a 5 mph increase at 60mph for the same given revs. Whilst not earth shattering the engine doesn't have an abundance of power and I'd be happy with it that.


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## Byronic (Apr 5, 2017)

I've shown the tyre sizes incorrectly the 709d has the 225 and the 609d has 215. The rim specs are given as being the same though, I don't know why a 709d rim should foul and a 609d doesn't as in your example. Perhaps the tyre profiles had something to do with it.


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## BrightonRider (Apr 5, 2017)

Haven't owned the van long but was pleasantly surprised at how nippy it was. I was expecting the worse from the internet threads I read but we have had it up to 70mph and whilst noisy, due to the RPM, it didn't slow on hills. I am confident the larger tyres will be fine.


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## mark61 (Apr 5, 2017)

BrightonRider said:


> Haven't owned the van long but was pleasantly surprised at how nippy it was. I was expecting the worse from the internet threads I read but we have had it up to 70mph and whilst noisy, due to the RPM, it didn't slow on hills. I am confident the larger tyres will be fine.




Swings and roundabouts, certainly lower RPM on the flat, you'll be changing down earlier on hills, acceleration in top gear will be reduced and probably top speed too, unless going downhill ;P.  May all be a price worth paying for reduced cruising RPM though. 

I've increased tyre size (height) on my last 3 vehicles, the current one by 8% and can notice a difference in ooomph at top end.


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## r4dent (Apr 5, 2017)

All that is really relevant is the rolling circumference of the tyre.  If you fit bigger wheels and lower profile tyres there may be no change.

Other things to consider when making a change to a larger circumference:- 
1) The speedometer will under read (e.g. it will show 50 mph when you are doing 60 mph) and as well as increasing the likelihood of tickets this is illegal

2) The odometer will under read (e.g. it will say 50 miles traveled when you've actually done 60). You will think your fuel consumption has rocketed , it hasn't.

3) A tyre size / wheel side change is considered a “modification” by some insurance companies in the UK. The insurer needs to be contacted, before making a purchase, to verify that they will continue to insure the vehicle once upgraded.


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## BrightonRider (Apr 7, 2017)

Thanks the input so far. I have bitten the bullet and bought 7 sprinter wheels. Will update once fitted.


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## Unimog (Apr 12, 2017)

*Fitting 16 Inch Merc rims to a Hymer 410D S670( 1990)*

Hi 
I have fitted 16" Merc steel rims to my Hymer S670 on Mercedes 410D Chassis cowl (engine type 602 5 cylinder 2.9 litre diesel ) 1991 Model 4600kg GVW (6.7m long A class with rear bed and/or seating ) in 2012

I got the 7nos Merc 609 steel rims from a commercial scrapyard in North Manchester with old, worn out 225/75/R16 tyres on.

A trial fitting showed these wide tyres fouled both front and rear leaf springs.

I arranged to fit 7 nos new Avon Avanza 185/75//R16C (104 rating = 900kgs per tyre) (the old tyres were R14" / 185 width )
They all fitted fine and our local fitters carefully checked at full lock and with bounce checks that nothing fouled anywhere on front and rear chassis.

To date nothing has grounded /touched/scraped on the road or on any of the rough tracks that I have used the van on. The 104 weight ratings are fine for my van weight ( 4600KG)

I now get exactly 63mph (sat nav checked) at 3000rpm on the 2.9 litre (non turbo) 602 engine which, for us, is a comfortable cruising speed 

Fuel consumption is around 22mpg for my driving style on the open road. It’s a lot less around town.

I have also installed an A class noise barrier kit from Steve at noisekiller.co.uk (This really helped reduce noise in our van, as there is only a single plywood skin under the original front Hymer dash)

I cleaned all the surface rust off the used 7 rims and rattle-can primed and silver sprayed them, finished off with 2 spray cans of clear laquer over the silver. (Halfords) – still nice a shiny and clean after 4 years 

The wheels appearnce still looked ugly with bare nuts, so Motoramahull supplied me with lovely stainless trims which fit the 609 wheels exactly and set the van off nicely

So if your wide tyres are still good and serviceable then you might have to choose to buy narrower width tyres _or get the angle grinder out on the rear springs. Be aware they could be weakened by this grinding and snap eventually_

Unimog


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## BrightonRider (Apr 12, 2017)

I now have the wheels. I will fit them in the next couple of weeks and update the thread.


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## ROVING MEG (May 13, 2017)

*Larger wheels*

With reference to the larger wheels --I have an s 700 1992 fitted with 16 inch wheels when first fitted they had large Michelin lorry type tyres --the advantage was the lower revs yet more than this was the gyroscopic effect keeping the van straight without too much steering input unlike the 14 inch wheels , however the tyres became obsolete and now these rims are fitted with 4x4 tyres where the profile is less and not so heavy now the gearing is slightly less too, 
I would not revert to the 14 's as I like the better cruise revs yet as always its the long inclines that slow it down - on the flat better handling and quieter cruise , another point is the ground clearance is better and working underneath if required is a doddle


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## BrightonRider (Jun 2, 2017)

I have now fitted the 16's and am very happy with them. Quieter cruising and nicer handling.


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## Chuckster (Jul 29, 2018)

BrightonRider said:


> I have now fitted the 16's and am very happy with them. Quieter cruising and nicer handling. [What year Sprinter did you use, what size tyres, what percentage gearing gain did you get, how is the driving please]


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## ROVING MEG (Aug 7, 2018)

*hymer s700 16 inch wheels*

Havnt logged in here for some time yet have noticed the 14/16 inch wheel debate -I upgraded to 16" some while back and love the difference on the cruise but what made a real difference was to remove the fuel tank filter and fit an in line in fact two in tandem on the supply pipe  thats the second Mercedes I have owned where the fuel filter was restricting the performance so if you have never looked drop the tank and remove or at least clean it


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