14 replies to this topic

[Land-roamer]

Hi all,
Happy 2011!
Planning a tire upgrade in the Spring.

Truck is now fitted with 6-7 year old 245/75/R16 range E tires. Some cracking gives me concern, so I'll get new trucks on the truck (96 Dodge 3/4 ton with helper springs and sway bar in the back) before heading very far with the Alaskan.

I'm debating on whether to stick with the stock tire size (245/75) or going up a bit (say, 265/75 or 285/75). One reason to consider going up is to get a taller tire which would lower rpm's a bit on the highway (have 4.10 gearing), and they are also a bit wider so have greater load capacity per tire (3400 vs 3040 pounds). One concern of higher tires (33 vs 30.5 in) is possibly more trouble jacking the camper onto the truck...

Any suggestions? Is 3040 pounds per wheel sufficient capacity in a range E tire to support the weight of a 10foot NCO Alaskan?
Thanks,
--Robert

[Barko1]

FWIW I went with 285's on my 99 F250 diesel to get a little extra height and the extra capacity doesn't hurt either. I put a piece of 2x6 under the jack to help with the lift. I have to get the camper high enough for the bigger tires plus it sits about 1.5" higher than the bed. I have Firestone Destination AT's with a 3750# capacity. http://www.tirerack....romCompare1=yes

[generubin]

I use 285/75/17 on factory steel wheels on my 2006 Dodge 4x4. No problem at all mounting the camper, nor jacking it off With your axle ratio, and especially if you have a diesel, you could use some lower rpm's! The difference between D rated and E rated is not necessarily weight carrying capacity but more precisely air pressure capacity. The D's are 65 pounds max, the E's are 85 pounds max.

[Kilroy]

I use 285/75/17 on factory steel wheels on my 2006 Dodge 4x4. No problem at all mounting the camper, nor jacking it off With your axle ratio, and especially if you have a diesel, you could use some lower rpm's! The difference between D rated and E rated is not necessarily weight carrying capacity but more precisely air pressure capacity. The D's are 65 pounds max, the E's are 85 pounds max.

Sorry, but I very strongly disagree with you about D vs E tire.

I went to a D tire because the 285 was rated the same as the 265 E rated tire I had. Truck ran fine empty. Treadwright tires were very good in snow and rain. Then I mounted Alaskan in spring. I knew I had a problem just going out of the driveway. The tires just didn't have the same capacity. I wouldn't even let the wife drive, the truck felt so squiriely. Had a very stressful trip to FL from WI.

Didn't want to spend the money, but put Goodyear 265 E rated tires on. Big difference. I had read about the difference between E and D even though rated the same, but didn't listen. Putting an Alaskan on your truck is a lot of weight, do not use D rated tires. Higher than D would be even better. It might have been ok with a Four Wheel or ATC camper which weights over a 1000 lb less.

I when I took off the 285 and put 265's back on, I noticed a documented increase of 1.5 to 2 mpg. Reason I had went to larger tires was I thought I'd get a mpg increase, which I didn't see. And this is with a 4.10 ratio also. I don't know why, but that is what I found in real life.

[natjwest]

I when I took off the 285 and put 265's back on, I noticed a documented increase of 1.5 to 2 mpg.

Would that be because the odometer needs to be adjusted to accomodate the larger diameter wheel? A larger tire would make the odometer/speedometer appear to be turning more slowly, which would make it appear that you're going fewer miles per gallon. Was this GPS documented or odometer documented? Or am I wrong about this?

[generubin]

Would that be because the odometer needs to be adjusted to accomodate the larger diameter wheel? A larger tire would make the odometer/speedometer appear to be turning more slowly, which would make it appear that you're going fewer miles per gallon. Was this GPS documented or odometer documented? Or am I wrong about this?

You are correct. When comparing mpg of a 285 vs. a 265, you add 7% to the 285 calculation.

[Kilroy]

Would that be because the odometer needs to be adjusted to accomodate the larger diameter wheel? A larger tire would make the odometer/speedometer appear to be turning more slowly, which would make it appear that you're going fewer miles per gallon. Was this GPS documented or odometer documented? Or am I wrong about this?

When I compared odometer to GPS I found I needed to add 6% to miles traveled with larger tires. Odometer is very close with 265's. Mileage was calculated with corrected miles driven.

[UglyScout]

The difference between D rated and E rated is not necessarily weight carrying capacity but more precisely air pressure capacity. The D's are 65 pounds max, the E's are 85 pounds max.

True and not true - There are D rated tires with the same weight rating as similar E rated tires. But when you go to E rated tires you get another rating up in the sidewall category from "8-ply" to "10-ply". Not that they have 10 sidewall plys anymore (probably 2 or 3) - but it is a stiffer sidewall eitherway.

[Land-roamer]

True and not true - There are D rated tires with the same weight rating as similar E rated tires. But when you go to E rated tires you get another rating up in the sidewall category from "8-ply" to "10-ply". Not that they have 10 sidewall plys anymore (probably 2 or 3) - but it is a stiffer sidewall eitherway.

Thanks to all for your thoughts on my questions.
I definitely will go with an "E" rated tire, that extra sidewall firmness and stability is worth it I feel.
About MPG with 285 vs 264 (or stock 245 on my Dodge), I have read that part of the MPG loss with taller/wider tires is due to the wider tire, and I suppose additional friction of them making contact with the road.
I'll probably go with 265/75 configuration in "E" rating of course. Probably a good compromise (keep engine revs down a bit, maintain good MPG).
All the best,
--Robert

[Clark]

Okay. I am new and will be picking up a 1997 10' CO Alaskan in a few weeks. I drive a 99 Dodge 3/4 ton Diesel. I have firestone airbags on the back, as well as a Helwig rear sway bar. I also have new Rancho 5000 shocks all the way around. I also have the 2 inch leveling kit n my truck. I have Level 8 tracker wheels that are rated at 3650 lbs if I remember correctly. Sounds good so far?

My question is the tires. I have Hankook Dyna Pro 315/75/R16 tires. With the above stated modifications, are these tires okay? The camper wieghts 1950 Dry. Do I need to buy E rated tires?