Tire size question.....

[NASA42]

We have a 2007 Casita Spirit 17' with 205/75 R14 Goodyear Marathons that are over 6 years old.. Replacement is days away.


I really don't want to go to 15' tires and wheels (and axle work). Is there room in the wheel wells for 215/75 R14....which also give a load capacity of over 1850 lbs?


Thanks.


Frank

[Roy in TO]

There are tire charts online that will provide you with the dimensions, manufacturer sites will give you the specs.

Why not replace them with the same size?

[NASA42]

Roy.....

Just felt a little more reserve load capacity couldn't hurt.

Frank

[Brian B-P]

The axle capacity of a stock Casita 17' is 3500 pounds, and the maximum capacity of an ST205/75R14 is 1760 pounds... just barely adequate to use the full capacity of the axle, which is why this is the size commonly provided by trailer manufacturers with this common axle capacity.

If the trailer is loaded near the limit of the 3500 pound capacity axle, and especially if it is unevenly loaded side-to-side, there is little if any tire capacity margin. Thus, the interest in additional tire capacity by Casita 17' owners. According to their website, Casita now equips the 16' and 17' models with 15" tires (of an unspecified size).

On the other hand, none the Casitas which Frederick has weighed and reported in http://www.fiberglassrv.com/forums/f...rld-43010.html even get close to the 3500 pound axle limit, so for those owners there should be no problem with tire capacity.

An ST215/75R14 Load Range C has a maximum capacity of 1870 pounds (as mentioned above)... higher, but only 110 pounds per tire higher.

[Thinh]

One of my input through pulling a trailer with high speed on high way: Remember if your trailer having smaller size of tires compared to your TV tires. When driving on highway with high speed, one rotation of your TV wheel could ended up 2 or 3 turns of your...trailer wheel. With high speed driving, in particularly summer time when it's hot, the air inside of your tires becomes HOT quickly. The temperature of internal air of tires is proportional to your speed. Depend on how good your tires are, ONE OF TRAILER TIRES COULD BE EXPLODED regarding to hot weather, high speed and smaller size of your trailer's tire size. Just my thought...

[honda03842]

There is much that can be done to improve tire performance. We have had very good performance from our 13" tires but we are conservative towers.

As Brian suggested side to side load balance is one. We match tire pressures from side to side and check to seenthat they have the same tire patch on each side. We have temperature monitors on our tires. We try to drive early in the morning when it's cooler, generally don't drive more than 4 hours a day and don't drive higher than 62 mph, staying under the tires speed limit, and usually at 55 mph.

[Brian B-P]

Originally Posted by Thinh

One of my input through pulling a trailer with high speed on high way: Remember if your trailer having smaller size of tires compared to your TV tires. When driving on highway with high speed, one rotation of your TV wheel could ended up 2 or 3 turns of your...trailer wheel.

The rotational speed of the trailer tire depends on its overall diameter and the speed it is going down the road. The size of the tow vehicle's tires is irrelevant.

Perhaps Randy is trying to explain that trailer tires are small and thus turn faster than you might expect: okay, but few trailer tires are only half or less the diameter of the ones on the tug... unless you tow a tiny tent trailer with a monster truck. On my van/Boler rig, the tug and trailer tires are nearly the same size.

Originally Posted by Thinh

With high speed driving, in particularly summer time when it's hot, the air inside of your tires becomes HOT quickly. The temperature of internal air of tires is proportional to your speed. Depend on how good your tires are, ONE OF TRAILER TIRES COULD BE EXPLODED regarding to hot weather, high speed and smaller size of your trailer's tire size. Just my thought...

Yes, high speed causes heating, which is one reason that all tires have speed ratings. Stay within that rated limit, with adequate inflation pressure, and there is no problem. There is certainly no reason to panic about "EXPLODING" tires!

[Tom Trostel]

When facing the same challenge, I went online to tirerack.com and ordered 3 Kumho Radial 857 tires in size 195R14C. They have a diameter of 26.2 inches and ST205/75/14 have a diameter of 26.1 inches. The Kumhos have a load rating of 2094 lbs. I had these mounted and balanced by a local tire shop when they arrived 2 days later. With 3 years use on my 17' Bigfoot, zero problems.

http://www.tirerack.com/tires/tires....4857&tab=Sizes

[NASA42]

Thank you, everyone.


My base question's been answered (yes, the 215/75 14's will fit), and the additional facts and info are appreciated.


I believe I will go (slightly) larger to the 215's, and keeping the towing below the ST speed limit just makes good sense.


Hope to see you down the road.


Frank