Community Forums

sleestac · 02-03-2014, 04:54 PM

I am looking to replace tires on the Coachman 30' and am curious if anyone has done this or would shy away from it. I found this on another site. Seems logical, but who knows. The prices on the two tires is about the same. I am in Florida and most of my time is here in the south.

OEM size is 225/75/16R. The post I read recommended going to a 215/85/16R.

"215/85/16R tires are larger in diameter (about 1.2 inches taller) and slightly narrower. This means they increase vehicle ground clearance by about 0.6 inches, increase gas mileage slightly by raising the ratio in every gear including over-drive, and improve rear dual-set tire cooling in warm weather because there is more air space between the adjoining dual tires' sidewalls."

Any thoughts?

reitrof · 02-03-2014, 05:16 PM

Do you have a link to the article?

One concern would be a taller sidewall with more flex. I assume you would replace the fronts as well. Might make handling a bigger issue.

Anyone gone down this road? sorry for the pun

Skip426 · 02-03-2014, 05:17 PM

This may not be an issue in flat country; FL ; but in hills, the increase in height/ gear ratio, can lead to increased down shifting & more time spent in a lower gear. That would kill any fuel savings.
Do both tires have the same load rating, usually a taller side wall makes for a lower rating due to side wall flex.

sleestac · 02-03-2014, 05:48 PM

I was planning on replacing the front as well. You bring up a valid point about the flex. may just go ahead with OEM size. I am looking to do some travelling in north Ga and NC so I will do some hills.

This the link from the other site.

Woodalls Open Roads Forum: Class C Motorhomes: New tires? Help me decide?

reitrof · 02-03-2014, 07:34 PM

Not sure Skip. The comments are aimed at someone with a small class C. What size is yours?

Murf2u · 02-04-2014, 05:18 AM

I'd be very skeptical of any article that makes claims like "improve rear dual-set tire cooling in warm weather because there is more air space between the adjoining dual tires' sidewalls".

The tires create heat from the friction of the road and the constant flexing they do as they roll. But the faster they roll, the faster the air movies across them. Next time you pull off the highway put your hand on a tire, it won't be very warm at all.

Skip426 · 02-04-2014, 10:46 AM

Quote:

Originally Posted by reitrof

Not sure Skip. The comments are aimed at someone with a small class C. What size is yours?

Class C , A , any TV, any change of engine RPM to vehicle speed, can change the transmission shift pattern, by dropping the engine out peak torque range and 2 to 300 RPM can be enough to do that particularly when a vehicle is being operated near or at Max. GVWR/ GCWR. which is where most RVs are being operated.
Having owned a TV that was geared wrong, keeping the engine operating in it's sweet spot as far as RPM is concerned , has been a consideration ever since.