Bigger tires any issues I should be aware of? (1 Viewer)

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All complete new guy when it comes to moding. I recently took delivery of my new GX and have been kitting it out with things here and there. I have a very old daily driver and this vehicle is the family adventure vehicle which I’ve been saving up a very long time for.

I recently placed a deposit on some new rims/tires. Looking to go from the stock 265/55/R19 which from research is a +25 offset 7.5 inch width rim to a 265/70/R17 on a zero offset 8.5 inch width rim. (Method 703s)

First question, I am aware the Speedo is going to be a little off, I guess I’m fine with that. But I was reading it could cause transmission issues down the road (due to shift timing/speed). Like I said this is a brand new vehicle so first not
looking to void any warranty and second don’t want to screw anything up since I would like to keep this for as long as possible. Especially since I’m going to be paying on it for a while

Any advice, wisdom you all can provide I would appreciate it. Are these accurate concerns?

Thanks.
 
The wheels and tires should fit fine but you may need to to heat gun some of the liner back if there’s a little rubbing. A lot of GX’s running that tire size and I’ve never heard of transmission issues due to that. Running that tire size my speedo was almost right on compared to my phone app and gps device. I’ve heard the speedo can be a little on the slow side from factory.
 
Use this 4 wheel drive calculator to determine your percentage increase.


Your transmission will have not shift into 6th gear as much, such as hill climbs and strong head winds. The bigger the tire the more noticeable it becomes. Long term damage perhaps, but 100,000-200,000 miles? Who knows? I can attest that the transmission will run warmer. I have been observing mine for the past two years, before I installed the factory transmission cooler it would quickly warm up, much faster than stock. Once I installed the cooler it improved temps dramatically. In extremum temps, hill climbs (at freeway speeds), or headwinds the temp still rises high in the 220-225 range.

My build is at the extreme of the vast majority here with fully armored and kitted out. The final correction for this is to regear. I have had gears on order since October 1st, hopefully soon.
 
Use this 4 wheel drive calculator to determine your percentage increase.


Your transmission will have not shift into 6th gear as much, such as hill climbs and strong head winds. The bigger the tire the more noticeable it becomes. Long term damage perhaps, but 100,000-200,000 miles? Who knows? I can attest that the transmission will run warmer. I have been observing mine for the past two years, before I installed the factory transmission cooler it would quickly warm up, much faster than stock. Once I installed the cooler it improved temps dramatically. In extremum temps, hill climbs (at freeway speeds), or headwinds the temp still rises high in the 220-225 range.

My build is at the extreme of the vast majority here with fully armored and kitted out. The final correction for this is to regear. I have had gears on order since October 1st, hopefully soon.
Thanks for the info. The size difference is only 1.1 inch so nothing crazy. Plus I have a trans cooler on there now so maybe it should be fine 🤔
 
So I used the calculator @Washingtontaco provided and the difference in gear ratio is 0.141. Stock is 3.909 and with the new tires size it’s 4.05. Seems minor to me, but I’m not a mechanical engineer or expert. When is a regear needed? Is there a certain threshold in which you need one. Or once you are out of spec you should get one?
 
All complete new guy when it comes to moding. I recently took delivery of my new GX and have been kitting it out with things here and there. I have a very old daily driver and this vehicle is the family adventure vehicle which I’ve been saving up a very long time for.

I recently placed a deposit on some new rims/tires. Looking to go from the stock 265/55/R19 which from research is a +25 offset 7.5 inch width rim to a 265/70/R17 on a zero offset 8.5 inch width rim. (Method 703s)

First question, I am aware the Speedo is going to be a little off, I guess I’m fine with that. But I was reading it could cause transmission issues down the road (due to shift timing/speed). Like I said this is a brand new vehicle so first not
looking to void any warranty and second don’t want to screw anything up since I would like to keep this for as long as possible. Especially since I’m going to be paying on it for a while

Any advice, wisdom you all can provide I would appreciate it. Are these accurate concerns?

Thanks.
Another issue is the spare tire. You want to have the same size spare or it can cause problems. I also have 265/70/17 and a stock tow hitch. The spare would not fit without KDSS spacers.
 
Another issue is the spare tire. You want to have the same size spare or it can cause problems. I also have 265/70/17 and a stock tow hitch. The spare would not fit without KDSS spacers.
Excuse my ignorance. Why did you
Need KDSS spacers for the spare tire? Does the bigger tire in the spare location hit those components?
 
Excuse my ignorance. Why did you
Need KDSS spacers for the spare tire? Does the bigger tire in the spare location hit those components?
The spacer moves the KDSS just enough to squeeze a larger tire in that space.
 
Going from OEM up to a 265/70/17 won't cause any issues with gearing/transmission feel. My speedometer was a little slow on the OEM tires and is now accurate per GPS after I switched to 265/70/17s. You may have to do some trimming on the back of the front fenders where the side skirt attaches to stop rubbing while turning.

If you have the OEM hitch receiver, your upsized spare tire likely will not fit in the factory tub so plan for an alternate solution like KDSS spacers, a swingout carrier, etc.
 
Going from OEM up to a 265/70/17 won't cause any issues with gearing/transmission feel. My speedometer was a little slow on the OEM tires and is now accurate per GPS after I switched to 265/70/17s. You may have to do some trimming on the back of the front fenders where the side skirt attaches to stop rubbing while turning.

If you have the OEM hitch receiver, your upsized spare tire likely will not fit in the factory tub so plan for an alternate solution like KDSS spacers, a swingout carrier, etc.

Same - it seems like my speedo is actually more accurate as well after switching.

As for fitting a spare, mine fits without modification (with Class IV OEM hitch), but your mileage may vary based on the tire you choose.
 
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I have a 265/70/17 spare tire on an FJ Cruiser rim that fits with the IV hitch. The tire is a street tire without chunky tread, a tire with taller treads or a wider rim may not fit as well.
 
So I used the calculator @Washingtontaco provided and the difference in gear ratio is 0.141. Stock is 3.909 and with the new tires size it’s 4.05. Seems minor to me, but I’m not a mechanical engineer or expert. When is a regear needed? Is there a certain threshold in which you need one. Or once you are out of spec you should get one?
That is not much and probably negligible. Beware of tire creep!
 
I have OEM hitch and a brand new Wildpeak AT3W in 265/70 that fits in the spare location.
 
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You don’t need to regear… for whatever this is worth:

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Edit - just for reference, this assumes 65 mph in drive ratio (1.00, which would be 4th gear).
 
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To those mentioning that your spare did/did not fit in the stock location with a hitch, which hitch do you have? The GX460's have two hitches from the factory, one more burly than the other for heavier-duty towing use.

Which tow hitch are you running to fit/not fit a 265/70?
 
To those mentioning that your spare did/did not fit in the stock location with a hitch, which hitch do you have? The GX460's have two hitches from the factory, one more burly than the other for heavier-duty towing use.

Which tow hitch are you running to fit/not fit a 265/70?

Been discussed to death. Check this thread......

 
Been discussed to death. Check this thread......

Thanks for that!

I was also nodding to the subjectivity of "my X tire fits with a hitch" comments. There are too many variables to make blanket statements like this is all.
 
Thanks for that!

I was also nodding to the subjectivity of "my X tire fits with a hitch" comments. There are too many variables to make blanket statements like this is all.
roll under your truck for 5 mintues with a tape measure, and you'll immediately come to the same conclusion as everyone else does - that any meaningful tire size upgrade will not fit under the truck, and the hitch isn't the only problem. that's probably why no one sweats the details of Class III/IV hitch, OEM/Curt etc. the cost/half-inch to fit a spare larger than 31.5" is staggering. Just staggering. It's probably the most expensive bang-for-the-buck upgrade on these rigs.
 
roll under your truck for 5 mintues with a tape measure, and you'll immediately come to the same conclusion as everyone else does - that any meaningful tire size upgrade will not fit under the truck, and the hitch isn't the only problem. that's probably why no one sweats the details of Class III/IV hitch, OEM/Curt etc. the cost/half-inch to fit a spare larger than 31.5" is staggering. Just staggering. It's probably the most expensive bang-for-the-buck upgrade on these rigs.
For sure! But the hitches do play a part in the whole being that the different class hitches are vastly different in comparison regarding their under-body space requirements. I'm in agreeance with everyone here, but there are variables that some seem to be forgetting to point out. We all don't have the same options underneath.
 

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