Need help after changing to BFGoodrich KO3 265/70R17

[tawfiqi]

As a summary before you read: do I need a tune, and what PSI.

Hello, and thank you all in advance.

The factory wheels are the same as (2022-2025 TOYOTA TUNDRA FACTORY OEM 18" CHARCOAL ALLOY WHEELS RIMS 95952) which came with Yokohama Geolandar A/T G31 size 265/65R18.

And i have just switched to Method MR70378560535 and BFGoodrich KO3 265/70R17 (To be specific LT265/70R17 118/115S Load Range D).

Unfortunately, the exact KO3 model does not come to the US, therefore I wasn't able to get information from BFGoodrich.

What PSI should I be using for everyday, light-load driving?

And after changing the wheels/rims and tires, do I need a tune?

As for the tune, based on my research, and some help from chatgpt i came up with this summary, but would appreciate your recommendation as this is my first Toyora.
with those wheel and tire changes, there was no weight different neither over all sizes, and I should not require any tuning. Is that correct?

Thank you all,
Abdullah

 

[RideWithYanu]

For PSI, if you’re very particular you could do a chalk test. I would just air them to 35-38 PSI for the tarmac, and deflate as needed when off tarmac. You definitely don’t need a tune for this setup, though you may notice a slight amount of sluggishness with the heavier tires.

 

[5Runner]

They can’t recalibrate the computer to account for the larger tires can they? You just live with the % difference on the speedo?

 

[Blue Bear]

As a summary before you read: do I need a tune, and what PSI.

Hello, and thank you all in advance.

The factory wheels are the same as (2022-2025 TOYOTA TUNDRA FACTORY OEM 18" CHARCOAL ALLOY WHEELS RIMS 95952) which came with Yokohama Geolandar A/T G31 size 265/65R18.

And i have just switched to Method MR70378560535 and BFGoodrich KO3 265/70R17 (To be specific LT265/70R17 118/115S Load Range D).

Unfortunately, the exact KO3 model does not come to the US, therefore I wasn't able to get information from BFGoodrich.

What PSI should I be using for everyday, light-load driving?

And after changing the wheels/rims and tires, do I need a tune?

As for the tune, based on my research, and some help from chatgpt i came up with this summary, but would appreciate your recommendation as this is my first Toyora.
with those wheel and tire changes, there was no weight different neither over all sizes, and I should not require any tuning. Is that correct?

Thank you all,
Abdullah

Long story short - LT tires are inflated to the same pressure whether they are C, D, or E load. The difference between the tires is the maximum inflation pressure, which increases from C to D to E, with E having the highest possible inflation pressure because they can support the greatest load.

For a load of 2100 lbs (which is equivalent to the OEM SL load tires), you'd be at 40-41 psi. If you want the details of how I arrived at 2100 lbs, then go to my prior post. The load tables are based on the ETRTO tables and should be the same pretty much anywhere in the world. If in doubt, do a chalk test as suggested by @RideWithYanu .

I'm running Falken WildPeak AT4W (E-Load) in LT255/80R17 and have no issues with my speedometer reading (which is nearly dead on with the slightly larger tires, which are 33" diameter.) In your case, a 265/65R18 and a 265/70R17 are both 31.6" diameter, so your speedo reading should remain unchanged.

I'm not sure which engine you have in your LC250 since it is not a U.S. version, but the gasoline 4-cylinder turbo hybrid is more than powerful enough to run the KO3 you chose without significantly impacting performance.

 

[tawfiqi]

They can’t recalibrate the computer to account for the larger tires can they? You just live with the % difference on the speedo?

The speedometer was already off from factory for about from 5-9kmh/3-5.5mph while testing with some gps devices (speedo 136km/h while gps 127km/h). And i have lived with that, to be honest it's an advantage while you speed near the speed cameras without noticing.

The new tires shouldn't be any larger, only pattern differences as i went to 70R17 instead of 65R18.

I tested today and there were no changes with the speedometer before/after the new tires and rims.

 

[tawfiqi]

Long story short - LT tires are inflated to the same pressure whether they are C, D, or E load. The difference between the tires is the maximum inflation pressure, which increases from C to D to E, with E having the highest possible inflation pressure because they can support the greatest load.

For a load of 2100 lbs (which is equivalent to the OEM SL load tires), you'd be at 40-41 psi. If you want the details of how I arrived at 2100 lbs, then go to my prior post. The load tables are based on the ETRTO tables and should be the same pretty much anywhere in the world. If in doubt, do a chalk test as suggested by @RideWithYanu .

View attachment 44418

I'm running Falken WildPeak AT4W (E-Load) in LT255/80R17 and have no issues with my speedometer reading (which is nearly dead on with the slightly larger tires, which are 33" diameter.) In your case, a 265/65R18 and a 265/70R17 are both 31.6" diameter, so your speedo reading should remain unchanged.

I'm not sure which engine you have in your LC250 since it is not a U.S. version, but the gasoline 4-cylinder turbo hybrid is more than powerful enough to run the KO3 you chose without significantly impacting performance.

Firstly i appreciate the time you have taken writing this.

As for the PSI, you seem right with 40-45, visually appealing from the tire pattern, and not 33 as the tire dealer informed me (i know they do not understand the psi changes with the tire, had my experience with my previous vehicle).

The chalk test seems the best and easiest solution, will try doing that.

-

As for the vehicle, our version is the 2.4L turbo 4-cylinder (267hp) non-hybrid.

As per my best knowledge and search, both old and new wheels and tires should have almost the same weight. (Hopefully)

I tested today and there were no changes with the speedometer before/after the new tires and rims.

 

[imann777]

They can’t recalibrate the computer to account for the larger tires can they? You just live with the % difference on the speedo?

The only drawback bigger the tire can slightly affect speedometer accuracy and fuel economy.

 

[tawfiqi]

The only drawback bigger the tire can slightly affect speedometer accuracy and fuel economy.

The tire should be the same size, i went one size up to 70 but went down on the wheel to 17.

And based on my best findings, the weights should be almost the same, at most 5-10lb extra.

As you're in the UAE, and we here work the same way in Kuwait, do you think no tune is needed?

 

[imann777]

If your downsizing, then on the speedo would reader a bit faster . Eg if your doing 100Kmph shown on speedo, actually it would -2 to -3kmph , that roughly 97-98. You may loose a bit of ground clearance on OEM setup, But ur absolutely at a better advantage. No tune required, in terms of wheel if the bolt pattern and offset remain same.
Mine FE truck was delivered with 265/70R/18. But now models are also being delivered with 20 inch rig with classic grill setup. I have not looked at the offset setup. But looks clean set up

 

[imann777]

Also in the weight when u compare u new size is lighter.

265/70R18	~45-50 lbs (20-23 kg)
265/70R17	~42-47 lbs (19-21.5 kg)

This is because of the internal dia. Though the width & aspect ratio is same. Probably the Load ply ratings will be different I guess. But u will have improved ride performance gain. And maybe a marginal fuel saving, Which I dont believe LC owners feel the pinch in Middle East.

 

[tawfiqi]

Also in the weight when u compare u new size is lighter.

265/70R18	~45-50 lbs (20-23 kg)
265/70R17	~42-47 lbs (19-21.5 kg)

This is because of the internal dia. Though the width & aspect ratio is same. Probably the Load ply ratings will be different I guess. But u will have improved ride performance gain. And maybe a marginal fuel saving, Which I dont believe LC owners feel the pinch in Middle East.

Thanks at first!

I am bit lost with this kind of topic, I have almost no knowledge in it.

WIthin my best findings, and some deep searches with chatgpt, I have attached a table of the summary between my before and after changes. I have also attached a picture of the stock wheels, for your reference as i believe you should be having the same ones in the UAE.

As for the speedometer, since i have purchased the vehicle, at 136km/h on the speedometer, the gps on multiple devices was showing that i am at around 128km/h. And at 80km/h, the gps was showing about 75km/h. So it's off by 5-8 km/h. After the tire and wheels changing, the speedometer still off by the same numbers, no changes up or down.

By these info, i should not require any re-gear tuning, correct?

Appreciate your assistance on this.

 

[RideWithYanu]

Thanks at first!

I am bit lost with this kind of topic, I have almost no knowledge in it.

WIthin my best findings, and some deep searches with chatgpt, I have attached a table of the summary between my before and after changes. I have also attached a picture of the stock wheels, for your reference as i believe you should be having the same ones in the UAE.

As for the speedometer, since i have purchased the vehicle, at 136km/h on the speedometer, the gps on multiple devices was showing that i am at around 128km/h. And at 80km/h, the gps was showing about 75km/h. So it's off by 5-8 km/h. After the tire and wheels changing, the speedometer still off by the same numbers, no changes up or down.

By these info, i should not require any re-gear tuning, correct?

Appreciate your assistance on this.

Correct. I say this with good will: you’re overthinking this! You don’t need a retune or regear with such a minor change.

 

[tawfiqi]

Correct. I say this with good will: you’re overthinking this! You don’t need a retune or regear with such a minor change.

Thank you! With multiple opinions from the people around me, i wanted to get more correct answers from people with knowledge.

It's my first wheel and tire change in any car, better be safe then sorry.

 

[RideWithYanu]

Thank you! With multiple opinions from the people around me, i wanted to get more correct answers from people with knowledge.

It's my first wheel and tire change in any car, better be safe then sorry.

I always appreciate thorough research (and I sometimes fall into “analysis paralysis” myself)!

 

[tawfiqi]

Sharing some images for the ones wondering how it looks!

 

[RideWithYanu]

Sharing some images for the ones wondering how it looks!

Looks fantastic!

 

[imann777]

I always appreciate thorough research (and I sometimes fall into “analysis paralysis” myself)!

You mentioned GPS devices being compared. May I know which one. Are these Portable ones . Then you may recalibrate those devices for better accuracy
For iOS - Goto
Setting-Privacy& Security-Location Service is toggled ON. Tap System System Services, Make sure Compass Calibration is ON. Tap back. Enabke Precise Location - Always ON. And Toggle Background Refresh. To align. This should work accurately. On Garmin Device, ideally do this outside in an open area. Aways from Cell Towers. . Google it how to and you should align both accurately.

 

[imann777]

Sharing some images for the ones wondering how it looks!

I like the bumper guards. Are these metal or plastic reinforced

 

[tawfiqi]

You mentioned GPS devices being compared. May I know which one. Are these Portable ones . Then you may recalibrate those devices for better accuracy
For iOS - Goto
Setting-Privacy& Security-Location Service is toggled ON. Tap System System Services, Make sure Compass Calibration is ON. Tap back. Enabke Precise Location - Always ON. And Toggle Background Refresh. To align. This should work accurately. On Garmin Device, ideally do this outside in an open area. Aways from Cell Towers. . Google it how to and you should align both accurately. View attachment 44533

All what you have stated is turned ON in my iPhone. I have tested the speed in iphone, android with different websites/Apps, and my garmin dashcam. They are all giving the same numbers, thus, i believe it's accurate.

 

[imann777]

All what you have stated is turned ON in my iPhone. I have tested the speed in iphone, android with different websites/Apps, and my garmin dashcam. They are all giving the same numbers, thus, i believe it's accurate.

Since your new tires are significantly different in diameter, some dealers may be able to reflash the ECU or use tools like Techstream to adjust the speedometer settings B. However, not all dealerships offer this service, and some may say it’s not adjustable unless the error exceeds Toyota’s broad tolerance range A. You may do it from Private workshops. Normally this does not deter warranty. So that the speedo aligns with the new specs