I drive a White H3 and want to add a Gobi Rack and get some bigger tires for my stock rims.

I have two questions for the guys here with knowledge on the subject.


1. How dramatic of a change in the mpg should I expect?

2. What are the best name brand and largest size tires that I can install on the extisting rims with no lift?

 

1)well, the "MPG" will drop because the tires are larger and therefore will read that you are actually covering less ground than you actually are.

for instance, a trip that I make a decent amount should take ~134 miles now only takes ~ 126 if I remember correctly (only have done it once on the new tires, so don't quote me!)

2) so basically you just want wider tires than stock? some people have put 315/75/16's on their factory rims, but I have been told by tire mounters that is dangerous as the tire could unbead itself in some situations. I went with an oddball size - 295/75/16, as its the largest tire I could find that would "fit safely" on the factory 7.5" wide rim. my tires are general grabber at2's but if you want to spring for the bfg's they make them in the same size --> www.tirerack.com will have them, even though I bought mine locally

edit: the tires I listed will raise up the truck, as they are taller tires than stock.

what tires do you have stock? the base's goodyears or the adventure's bridgestones?

 

A slightly wider tire is not likely to unbead itself. If anything, it is more likely to hold a bead. A norrow tire on a wider rim is in more danger of unbeading, than the other way around.

315/75/16 are only slightly wider than the stock 285's.

285/75/16 = diam. 32.8 section width 11.2 Section Height 8.4

315/75/16 = diam. 34.6 section width 12.4 Section Height 9.3

The only real concern with running something too wide on a narrow rim is running the correct air pressure. If you run what the sidewalls say, then you will likely wear the center of the tread too soon, (depending on the width factors of both). The way around it would be to run slightly less air in the tires, to make sure the center of the tread section, doesn't crown out too much.

Without any lift, I would probably recommend running a 305/75/16 vs the 315. But that's just me. I don't think the 315's would be a real problem, I'd just rather err on the side of caution. As for myself, I'll probably stick with the 285's. But, it's not my "wheeler" so I do have options.

 

Has anyone one seen or know of the "dangerous condition" caused by putting a 315x75x16 on the factory H3 7 1/2" wheel? I am getting ready to buy this size tire and would like to find out if it is dangerous. I do not plan on running below 20 psi.

 

skeet, read your thread, I think that will settle any doubt you have. 35's will have no problem at all on stock rims. I can probably list you 100 names or more of people with them on their h3 with no adverse effects. I ran 11.5" wide 35's on my dually and I had 6.5" wide rims. put 60,000 miles on it with no problems at all.

 

I personally agree with importkiller about the 35's fitting, however the place that I was getting my tires mounted didn't see eye to eye with me (and wouldn't mount the tires if I brought them there). So I figured that there must have been some reason for them to turn down money?? The other reason I chose the slightly smaller tire is because I have heard that the 35's will rub upon full lock, and my size was only slightly larger than the adventure package's tires, so I figured I'd be OK (I have to really do some work to get my car into the garage, LOL)

 

I dropped a few MPG's when I put on 315/75r/16's but the look and offroad advantages are well worth it for me. The only issue is slight rubbing on full right turn and minor crowning on the tire. Ive had them on for 9 months now , no problems, although I just put on some aftermarket shocks that really made a big difference. No more front end dip on hard braking due to a 2-1/2 turn on my T-Bars, and they really absorb the bumps now. My two cents,, if MPG is a concern dont get the 315's, stay with the smaller size. But I tell ya seeing a H3 with 35's in person is da-bomb

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Has anyone found a good way to re-calibrate the speedometer and odometer to adjust for larger tires?

 

They probably have strict liability issues, and therfore are not allowed by policy to mount them. For a large company, the few dollars they would have made, isn't worth it if someone claims it caused something (anything). I can't see how it would cause anything.. but they are covering their tushs.

Personally, I myself would probably run something slightly smaller because I don't like having rubs.. If I were going to use it for a primary wheeler, then I would get a suspension lift and run accordingly.

 

I also have 315x75x16 on mine and check out the video - no problems at all:

H3 tested