235/85-16 OK on Triple Axle Raptor?

kazuaki · 02-13-2015, 12:12 PM

Hey all, just experienced the first blowout on the stock tires on my 2013 Raptor 381lev. Stock size is 235/80-16. Has anybody with a triple axle setup likes this moved up to 238/85-16 without any clearance issues? I'm concerned a out clearance e between the tires. It seems the 238/85 size would give me a larger selection of LT tires to choose from.

**sourdough** · 02-13-2015, 12:53 PM

I have not made that swap. From what I can see the 235/85 is about 1" larger in diameter (tirerack.com). Also when you move from the 80 series tires to the 85 you are moving into passenger and light truck tires - that's why there are so many tire choices. They aren't the same as a trailer tire. Use the search bar in this forum and I'm sure you can find any number of discussions about that issue.

bobbecky · 02-13-2015, 01:07 PM

Actually, the 235/85 R16 tire that should be looked at, at least for an upgrade from the E rated ST tires, would be something like the Goodyear G614, an all steel, G rated trailer tire. These are called an LT tire, but are not intended to be on anything but a trailer. We upgraded on our two axle rig to the G614's, and the size difference will largely be un-noticed. Just make sure your wheels are rated for 3750 lbs/110 psi, to be able to fully utilize the tire. Being a 2013, your wheels should be OK, but still check. They are pretty pricey, but well worth the cost compared to the damage a blown tire can cause and the down time dealing with replacing a tire and fixing damage.

kazuaki · 02-13-2015, 01:11 PM

We camp mostly in the desert and pull the trailer through some sand. On occasion we have to air down truck and trailer tires until we get to harder ground. Would the G rated tires be able to handle that treatment as much as any other tire?

EricLynnAllison · 02-13-2015, 04:38 PM

I blew 3 tires in two weeks on my Raptor. I went to a truck tire place and they showed me how much cupping the tires I had left had grown and placed them next to a 238/85-16. The truck tire was shorter than the original tires which had significantly cupped. I went with the LTs all around. Now have 7000 miles on them. Clearance appears fine.

kazuaki · 02-13-2015, 04:43 PM

Which tires did you go with?

EricLynnAllison · 02-13-2015, 04:54 PM

Firestone Transforce HT

jtyphoid · 02-13-2015, 08:57 PM

I was uncomfortable with moving to a larger tire, especially with the way the shackles allow the axles to move.

After reading quite a bit about some of the options, I went with Maxxis tires of the same size as the original. Maxxis appears to have a good reputation.

kazuaki · 02-13-2015, 09:06 PM

I looked at the inside of the wheel when I pulled the flat off and see it is labelled as 3750lbs and 110psi. Maybe I'll look into the higher rated tires.

kazuaki · 02-14-2015, 04:25 PM

I just took a rough measurement and was surprised to see that with stock tires I only have about 2.5-2.75" between the tires. It doesn't seem like 85 series tires would fit unless these stock 80 series tires are taller than they should be.

**JRTJH** · 02-14-2015, 06:12 PM

There are a couple of threads regarding upsizing tires and some owners have found that modifications to the undercarriage, ie: moving or cutting away a part of the outrigger assemblies, must be done to provide the needed clearance to install even "slightly larger" tires. If I were you, I'd do some very serious and cautious measurements before I spent money on tires that would likely not clear the metal understructure that is located in the wheel wells.

If you do a forum search for "outrigger" and "wheel well clearance" you should find many of those threads.

Good Luck

kazuaki · 02-14-2015, 06:31 PM

I've seen those threads and looked carefully. On my 381 there are no outriggers or brackets directly over the tires. There's lots of clearance to the chassis everywhere. My only concerns is tire to tire clearance.

**chuckster57** · 02-14-2015, 07:32 PM

If the tires your considering are 1" taller and you have measured 2 1/2" between tires now, your clearance will be 1/2", Not enough IMO.

kazuaki · 02-14-2015, 11:08 PM

Actually, if the diameter is 1" more, then the radius of each tires is 1/2" more. So the gap would theoretically be 1.5". Even so, that doesn't seem like much. I'm not sure how much(if at all) the gap fluctuates as the suspension cycles or as you turn.

**chuckster57** · 02-15-2015, 03:41 AM

Your right, math wasn't my strong suit.

kazuaki · 02-16-2015, 11:54 PM

So, is anybody running the Sailun S637 on a triple axle Raptor (or similar) fifth wheel?

notanlines · 02-17-2015, 03:36 AM

Kazuaki, we left Tire Kingdom in Fort Myers yesterday with four new 637's on our Raptor. Total price installed with new high pressure valve stems (no cost) was $700. It lowered the distance between tires by 3/4 of an inch. The tires run 110 PSI and the tech (?) 80 PSI so we settled on 100 PSI until I can look into it further. In the meantime I boosted it to 110 on the way back to the RV park.

kazuaki · 02-23-2015, 10:29 PM

UPDATE: I got the Sailun S637 tires installed on Friday morning and went on a short weekend trip (just 60 miles round trip). The tires fit the trailer fine. I certainly wouldn't want them any larger, but I think they'll be fine. One of the stock 235/80-16 tires I removed was over 32" in diameter. Yes, it was over an inch larger in diameter than the rest of the tires. I'm guessing some of the belts under the tread area had failed or something. The new tires are incredibly heavy. I now have some concern that the stock spare tire winch is adequate to hold that heavy tire up. I may install some sort of removable safety bar or something under the spare as insurance against a winch failure.

**chuckster57** · 02-24-2015, 06:33 AM

So 7 tires.. Like buying tires for my dually!!

kazuaki · 02-24-2015, 07:48 AM

One thing I noticed, the trailer seems to pull easier, maybe due to less rolling resistance. I'm not sure if its just my imagination or what

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