Tire downsizing

[justinbeez]

Hey all, I'll keep it simple. I have the Ridge Grapplers in 35x12.5x18x9 -12 leveled on the bilsteins up front and ORP. I want to downsize to get rid of the rubbing. I've had Falken At3w on my previous truck. Would yall recommend their 295/70, or a 285/75. Thanks!

Side note: was just thinking, would the Falkens rub less at 35x12.5 with the less aggressive sidewall than the grapplers? Or just go to the 295/70 (34.2x11.6) 285x75(34.8x11.2)

 

[WXman]

I think you will find that a "35x12.50" will measure out around 34" tall when mounted and on a truck. This is only a hair taller than a 295/70, not enough to matter. If you want to avoid rubbing I'd go smaller than either of your options.

 

[TheWaterman83]

I'll throw you a curveball. A lot of people shy away from due to price but BFG KO2's are amazing tires. The improvement over my stock Duracraps was like driving a different truck.

295/70/18's are what I would recommend. They spec at 12" which is .5" less than the Falken's and it might just be perfect.

Literally they were improvements in every aspect for me: noise, wet traction, snow traction, turning in, etc. The only difference that could be construed as a negative is they ride a little rougher over bumps due to the stiffer sidewalls.

 

[HSKR R/T]

I think you will find that a "35x12.50" will measure out around 34" tall when mounted and on a truck. This is only a hair taller than a 295/70, not enough to matter. If you want to avoid rubbing I'd go smaller than either of your options.

Problem is, the rubbing has more to do with the width than the height. A 12.5 wide tire is close to 325 and 295 is an 11.5

 

[CalvinC]

Problem is, the rubbing has more to do with the width than the height. A 12.5 wide tire is close to 325 and 295 is an 11.5

Exactly. Width plus your negative offsets.

I say with a level go as tall a tire as you like as long as you keep it narrow. I have the 295/70r18 at stock height + stock wheels but wished I’d have gone 285/75r18.

 

[Shots]

Either should be a good choice.
I've to 285/75/18 on my truck now and ran the same size on my last Jeep. It's a great size. They're similar diameter to most "35's" while being narrower/lighter than their 35x12.5 counterparts. As the others have mentioned, the narrower width is likely what will prevent the rubbing, not so much the diameter.
These will be roughly 3/8" narrower than the 295's while being similar diameters. I'm not sure where you're located, but I try to keep my tires as narrow as possible (within reason, I don't want a wagon wheel on there). Mainly because we get a lot of snow and the narrower tire does better at cutting through to the ground for traction. I should note that is if you're off road in deep powder and trying to "float" on the snow, a wider tire will act like a snow shoe so may be better for that type of driving.

 

[Louhound88]

Problem is, the rubbing has more to do with the width than the height. A 12.5 wide tire is close to 325 and 295 is an 11.5

Yep. And ridge grapplers tend to measure out wider than most other 12.5" wide tires i've found. I had 35x12.5 ridge grapplers measure out to over 13" once mounted and on the truck.

I have 295/65R20s with a level and no rub. Yokohama Geolandar MT"s, measure out pretty narrow at around 11.8ish inches. So a 12" wide, pretty close to the stated width.

 

[WXman]

That's not my experience at all, and I've had a LOT of tires. More sets and sizes than I can remember. A 285 is an 11". 295 is 11.5". 305 is 12". And 315 like on the Raptor trucks is equivalent to a 12.50.

Sure, width matters and offset really matters, but height is a part of that equation too. When I was taking measurements for my last build I discovered that width+height was the formula that worked. I measured that I had 1.75" of space between my stock tires and mud flaps in the front, so my aftermarket tires change in width+height couldn't be more than 1.75". Since a 2" taller tire will only add 1" at any given spot around the tire, and a 1.5" wider tire would only add 0.75" of width on the outside sidewall, I was able to go up to a 295/60R20. It ended up fitting like a glove with no room to spare.

 

[Shots]

You're correct that the diameter matters too, and it certainly shouldn't be ignored. The negative offset the OP is running is also a factor (maybe even more so than the width). Many things go into fitting wheels/tires on a truck so we obviously can't say any one thing exclusively will make or break a good fit.
That said, based on the experience of various tires on these particular trucks, it seems the diameter can work without rubbing. I'm running 285/75/18 tires as are others on the forum, and I have no issues with rubbing. Those are 34.8" diameter, so if someone is having rubbing issues with a 35" diameter tire wider, it would suggest the width is the culprit.
Again, that's ignoring the offset of the wheel which may not be helping.
As for the tire width based on dimensional values alone. While your synopsis of the widths are reasonable and a good place to start, there are a few things to consider. Much like diameter, the sizes vary a bit by manufacturer. The dimensional sizes are a good general guide, but they are also effected by the width of the rim the tire is mounted on. So for example, if a 285 tire is 11" wide when mounted on an 8" wide rim, it will measure 11.4" wide when mounted on a 9" wide rim. The rule of thumb is 0.2" width change on the tire for every 1/2" change on the wheel. The thing occurs when going narrowing, just the opposite direction of course.

All that to say that 285 may not necessarily be 11" width and a 315 may not necessarily be a 12.5" width. Factoring diameter, width and offset all play into what fits and what hits. That's why there are so many threads on nearly every automotive forum. Because there isn't a magic number that fits every application, since other variable play into it too.

 

[HSKR R/T]

GEEner

You're correct that the diameter matters too, and it certainly shouldn't be ignored. The negative offset the OP is running is also a factor (maybe even more so than the width). Many things go into fitting wheels/tires on a truck so we obviously can't say any one thing exclusively will make or break a good fit.
That said, based on the experience of various tires on these particular trucks, it seems the diameter can work without rubbing. I'm running 285/75/18 tires as are others on the forum, and I have no issues with rubbing. Those are 34.8" diameter, so if someone is having rubbing issues with a 35" diameter tire wider, it would suggest the width is the culprit.
Again, that's ignoring the offset of the wheel which may not be helping.
As for the tire width based on dimensional values alone. While your synopsis of the widths are reasonable and a good place to start, there are a few things to consider. Much like diameter, the sizes vary a bit by manufacturer. The dimensional sizes are a good general guide, but they are also effected by the width of the rim the tire is mounted on. So for example, if a 285 tire is 11" wide when mounted on an 8" wide rim, it will measure 11.4" wide when mounted on a 9" wide rim. The rule of thumb is 0.2" width change on the tire for every 1/2" change on the wheel. The thing occurs when going narrowing, just the opposite direction of course.

All that to say that 285 may not necessarily be 11" width and a 315 may not necessarily be a 12.5" width. Factoring diameter, width and offset all play into what fits and what hits. That's why there are so many threads on nearly every automotive forum. Because there isn't a magic number that fits every application, since other variable play into it too.

Generally speaking, widths play more of a factor than height when trying to find one that won't rub. Most guys running 35's that have rubbing issues are running 35x12.5. your 285 is quite a bit narrower.

It's fun to play around with metric tire sizes to find what you want, especially when going to larger tires. As you pointed out you can still run a "35" inch tire but keep it narrow enough to not rub.

Yes, wheel offset makes a difference as well. And if running aftermarket wheels, hopefully the place you are purchasing from is knowledgeable enough to get your wheels that fit properly with the tires you want to run

 

[Shots]

Generally speaking, widths play more of a factor than height when trying to find one that won't rub. Most guys running 35's that have rubbing issues are running 35x12.5.

Exactly what I was thinking too. Diameter plays into it, but the width is usually what causes you problems.