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Old 12-12-2016, 05:12 PM   #1
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Sprinter-Sportsmobile tire pressure specs

We took delivery of our Sprinter-Sportsmobile about 5-6 weeks ago at SMB North. I have a question about the tire pressure recommendations for the vehicle. The van is a 3500 long wheel base extended body with the 11,030 GVWR. The Sportsmobile build is the EB110S with some modifications (no propane, no generator, extra alternator and no solar panels, are the big ones). According to SMB North, the build weighed in at 8213 lbs. The M-B tire pressure specs are 61 psi at all positions for both unladen and laden vehicles. The label affixed by SMB calls for 47 psi in the front tires and 70 psi in the rears. The M-B specs list the GAWR as Front= 4,410 lbs; Rear= 7,720 lbs. As a long time trailer camper, I have a copy of the tire pressure/load specs for a wide range of tires. According to the specs for the M-B tires (LT 215/85 R16 115/112Q Load Range E), the 61 PSI recommended by M-B is more than sufficient in the rear duals to significantly exceed the rear axle rating. OTOH, even 61 psi in the front tires is somewhat short of the front axle rating. I suppose putting 70 psi in the rears might improve the stability of the rear, considering there is some high mounted weight (cabinets and roof A/C), but I don't get the point of 47 psi in the front. I did not check the tire pressure until recently. I had my local M-B dealer install a dually tire valve kit and checked the tire pressure a few days later to ensure that all was well (BTW, the Tire-man dually kit seems to work quite nicely). They had inflated the tires to 61 psi each. The van seems to handle OK with the 61 psi. Does anyone have any insight into what is the source of the SMB tire pressure recommendations? (I have a call into Nancy at SMB, but she was out today).
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Old 12-13-2016, 02:12 PM   #2
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The tire sticker on the driver B door panel that specifies 47 front and 70 rear is by Mercedes as required by vehicle manufacturer on all vehicles. The 144" single low roof also has this same pressure spec, which seems to work fine. I find that higher pressure in the front negatively affects drivability on rough roads and same for higher pressure in the rear. From my experiences one can use lower pressure in the rear if not near max weight although with a much less noticeable affect on drivability.
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Currently converting 2016 170" 4x4 w/custom interior, electric system, hot water and air, and many other things. Past owner of 2007 Sprinter 2500 144" w/Sportsmobile Penthouse, Van Conversions interior and
solar, inverter, charger, house electrical by self.
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Old 12-13-2016, 08:59 PM   #3
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Thanks for your reply. By way of further update, I got a call back today from Nancy at SMB North. It appears that the 47/70 psi numbers on the sticker were a mistake. It sounds like somebody just used the numbers from a different model (pretty clearly a 2500) than my 3500 with the long wheelbase and extended body. The correct numbers are the 61/61 speced by M-B. This makes sense, I guess, because with only two tires in the rear, higher pressures would seem likely to be needed to support the weight, and lower pressures in the front would be OK since the overall GVWR of the van is much less than a 3500.
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Old 12-14-2016, 08:25 AM   #4
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OT slightly... what's your opinion of SMB North's workmanship?
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Old 12-14-2016, 02:42 PM   #5
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We're very happy with it. Because we live about 550 miles from Huntington, IN, when we picked up the van, we immediately went to a local campground and camped for two days, during which we tried out all of the equipment and features. We found one minor issue that they fixed before we headed home. We camped one more night on our return trip. We haven't camped since then for lack of time and the fact that winter is about here. In fact, I winterized the water system a couple of weeks ago. We will be camping in it again in Florida in January. Having owned a couple of mass-produced travel trailers, I can say that there is no comparison; the SMB workmanship is far better than what those trailers exhibited.
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