Changing Tire Size or Wheels? Read this first!

[BlackWorksInc]

Right, the scangauge type products do not adjust the actual speedometer, but they do have options to adjust their speed display and calcs for different tire sizes via a correction factor. The scan gauge does have a small screen... There is a cheaper option with a much better screen called an ultraGauge. Think it goes for about $70. It is larger, so the mounting options might be limited....but I have been thinking of picking on up and giving it a try. The speedoHealer sounds like another good option.

I wonder if the speedohealer approach would also correct the center display mpg and the ODO. I'm assuming it would. Most vehicles I've had in the past (with an open ECU...) just let you adjust the tire diameter parameter and everything works as expected. Sort of surprised that Toyota does not at least support this parameter. To me, its like not allowing you to program the tire pressure sensors when you swap those.

I imagine it should, since the other modules get the VSS signal off the CAN bus and/or from either the
ECM or Combination meter.

 

[jony.lisa]

Will this combination work

Hi,

Newbie here, I have read numerous times the enormous information on here for changing wheels and tires and my mind is overwhelmed to the point of wanting to just buy another set of stock tires for my limited rims! I have a 2010 magnetic grey 4Runner with no lift. I hate the "pizza cutters" this truck came with so I want to spring on some new rims and tires and finally have the wife's approval!

So attached is a combination I built on 4wheelparts.com and it consists of BFG All terrain ko2's @ 275/70/r17 and some rims that are 17" 6x5.5 @8" wide with backspace of 4.5" and offset @ zero.

Now the questions

Will it rub?

If so do I need a lift?(planning a spacer lift down the road)

What sort of modifications in the meantime to make no rub?

I can get these rims with 4.75 backspace but they are 9" wide with -6.6mm offset would that be better?

Mostly a soccer mom truck but we do go outback camping in the woods where there is no amenities.


Thanks in advance

Jonathan

 

[1engineer]

Hi,

Newbie here, I have read numerous times the enormous information on here for changing wheels and tires and my mind is overwhelmed to the point of wanting to just buy another set of stock tires for my limited rims! I have a 2010 magnetic grey 4Runner with no lift. I hate the "pizza cutters" this truck came with so I want to spring on some new rims and tires and finally have the wife's approval!

So attached is a combination I built on 4wheelparts.com and it consists of BFG All terrain ko2's @ 275/70/r17 and some rims that are 17" 6x5.5 @8" wide with backspace of 4.5" and offset @ zero.

Now the questions

Will it rub?

If so do I need a lift?(planning a spacer lift down the road)

What sort of modifications in the meantime to make no rub?

I can get these rims with 4.75 backspace but they are 9" wide with -6.6mm offset would that be better?

Mostly a soccer mom truck but we do go outback camping in the woods where there is no amenities.


Thanks in advance

Jonathan

Jonathan, please go back and re read the first post again. It was written as a basic primer for people exactly like yourself. What specific parts of the explanation don't you understand?

 

[jony.lisa]

Basically the offsets and back spacing requirements. I understand via the 5gen tire fitment guide that those tires in that size are in the "green" for no mods but that presumes stock rims with stock offsets and back spacing. I just don't know how to figure out if they will rub. Mainly what I don't understand is the offset set at 0.
What does that do to the tire at full lock compressed?

I understand stock backspace on the trail edition rims and sr5 rims is 4.5 to 4.875 but offsets are not mentioned in the tire fitment guide? So with my rims I've chosen with 4.5 backspace and 8" wide rim will work , because the 9" rim will not( going back over your original post says many dealers stopped offering them cause of othe issues) with my rim having a offset of 0 matter?

 

[wfo9]

Basically the offsets and back spacing requirements. I understand via the 5gen tire figment guide that those tires in that size are in the "green" for no mods but that presumes stock rims with stock offsets and back spacing. I just don't know how to figure out if they will rub. Mainly what I don't understand is the offset set at 0.
What does that do to the tire at full lock compressed?

I understand stock backspace on the trail edition rims and sr5 rims is 4.5 to 4.875 but offsets are not mentioned in the tire fitment guide? So with my rims I've chosen with 4.5 backspace and 8" wide rim will work , because the 9" rim will not( going back over your original post says many dealers stopped offering them cause of othe issues) with my rim having a offset of 0 matter?

Should work. Might need to push fender liner forward a bit. Really just depends on your alignment... Also, make sure the wheels are hub centric and you get the proper center bore size or adapter ring.

 

[Bilbo]

... 5gen tire figment guide ...

Priceless!

Seriously, thank you [MENTION=66316]1engineer[/MENTION], @wfo9, [MENTION=66389]BlackWorksInc[/MENTION], and the many others who make tr4.org both worthwhile and addictive.

 

[jony.lisa]

Should work. Might need to push fender liner forward a bit. Really just depends on your alignment... Also, make sure the wheels are hub centric and you get the proper center bore size or adapter ring.

Thanks wfo9,

It seems it doesn't matter how far in depth we go in explaining tire and rim upgrades there is always going to be a newbie! I've been following this forum for many a year, owned multiple toyotas and this is my second 4Runner owned from new this one. Original set of tires and 105000kms on the odo. Now it's old enough to put some upgrades into it. I will be doing many other upgrades as I want my now 3 year old son to have this truck for his 16th birthday. I hope there will always be guys like 1engineer and you around to bounce questions off of and Google of course. Will post pics here when installed and also the myriads of magnetic grey threads.

Cheers

 

[toyo]

http://www.toyota-4runner.org/4th-gen-t4rs/178078-speedohealer-v4-4th-gen.html

This was what I installed in my 4th gen, the basic concept is the same; you'd just have to find the wires in an electrical diagram.

It works well, the only thing to remember is this only corrects what the combination meter and ECM see for vehicle speed (which translates to your cruise and speedometer reading.).Because the Vehicle Speed datapoint is generated by the Skid Control ECU by averaging the wheel speed sensors then outputting a frequecy based waveform that the speedohealer offsets to give an accurate measurement. So the Skid Control ECU still sees the skewed/incorrect speed value even with the Speedohealer installed; so far the only way I can think of correcting the measurement into the SKid Control ECU, would be by making a 4 channel version of the Speedohealer that is spliced into each wheel speed harness.

I use the SG II to adjust my speedometer. It doesn't do anything for the actual speedo in the cluster but my SC is right in front of me and works great. Mine is off 9%.

 

[jony.lisa]

So this is my combo I went for. Moto metal 970 17x8 wrapped with BFG ko2. 275/70/r17. Had to do the fender liner mod but all is well now even when flexed out. Thanks all for the help. On a secondary note is 12oz of weight normal to balance this rubber? Got them to take the rubber off the rim and the rim is perfect but as soon as the rubber is put on 2 tires are 6.25oz of sticky weights inside the rim and 6.25 oz of clipped on weight on the the backside of the rim for a total of 12.5 on 1 rim! The other two have 3 oz and 2 oz.

 

[Randyosb]

i read this before I made my mods but now that I have-it is even better

 

[16blacktrail]

I have added this to the FAQ sticky. Please make sure to use this link to direct the new guys to when asking about tire size changes and rubbing. Thanks again @wfo9!

I'm a newb here and I'm hoping someone can answer my question about the tire size. I just recently put 275/70/17 k02 on the runner and I just want to
Know if any other changes need to be made or if this new set up will hurt anything because of the added size and extra mass of the tires. The runner feels like it's working harder at lower speeds so I'm not sure if this is normal. My other question is that it seems like the front is lower and I'm wanting to balance things out a bit, any advice on the best approach. I have heard of maybe 5100 up front and spacers in the back to raise it up a bit. Thanks everyone.

 

[1engineer]

Your front is actually higher now with the increased diameter. It might look lower because of the wheel well is now filled out more because of bigger tire.

When you put a heavier and larger tire you will suffer both in acceleration and efficiency. There is no cure for efficiency but you could re gear to make up the acceleration time. That's an expensive mod and you are really not needing it with only 275's.

Lift won't help you one bit.

 

[usmcvet]

that is good to hook thanks for the info.

 

[16blacktrail]

Your front is actually higher now with the increased diameter. It might look lower because of the wheel well is now filled out more because of bigger tire.

When you put a heavier and larger tire you will suffer both in acceleration and efficiency. There is no cure for efficiency but you could re gear to make up the acceleration time. That's an expensive mod and you are really not needing it with only 275's.

Lift won't help you one bit.

Thank you for the info, I'm not super concerned about the mpg being affected I'm just more concerned that it won't damage anything or cause more stress to the diff and other areas. Thanks again

 

[Blue15]

Sounds about right, that E rated tire weights 55 pounds according to tirerack.com, Our stock P rated, at least my Dunlap Crosscrap AT20 weight 39 pounds. So I suppose adding an extra 16 pounds per wheel would have that effect.

 

[SnrDisregardo]

Try using this Tire size calculator. You may have to be a member though....
https://www.tacomaworld.com/tirecalc

 

[1engineer]

Try using this Tire size calculator. You may have to be a member though....
https://www.tacomaworld.com/tirecalc

Works fine for anyone.

 

[mrtifftiff]

I recently got pulled over going 73 in a 70 and I had my cruise control pinned at 70. With my 285/65/18s I knew my speedometer was supposed to be off 3-4.5%, but every single time I drove past a radar speed sign in a school zone or around a curve, it would always read exactly the same on my speedometer and the speed from the radar. Any guesses? I assume the police cruisers radar is more accurate and the math says that my speedometer should be off so in the future I will slow down. Any logical reason the street sign radar dictators report false numbers or is it just user error? No ticket, at least.

 

[bloodninja]

I recently got pulled over going 73 in a 70 and I had my cruise control pinned at 70. With my 285/65/18s I knew my speedometer was supposed to be off 3-4.5%, but every single time I drove past a radar speed sign in a school zone or around a curve, it would always read exactly the same on my speedometer and the speed from the radar. Any guesses? I assume the police cruisers radar is more accurate and the math says that my speedometer should be off so in the future I will slow down. Any logical reason the street sign radar dictators report false numbers or is it just user error? No ticket, at least.

The difference in speed between stock size and your tire size would be 2.2 mph (70 vs 72). The radar sign dictators are a reasonably accurate representation which are designed to get you to monitor your speed and slow down. A trained person with a regularly calibrated piece of equipment is going to be more accurate. That said, the difference in speed told to you by the person pulling you over and your "adjusted speedometer speed" was less than 1 mph.
I'd encourage you to monitor your speed more closely :cowboy:

 

[mrtifftiff]

The difference in speed between stock size and your tire size would be 2.2 mph (70 vs 72). The radar sign dictators are a reasonably accurate representation which are designed to get you to monitor your speed and slow down. A trained person with a regularly calibrated piece of equipment is going to be more accurate. That said, the difference in speed told to you by the person pulling you over and your "adjusted speedometer speed" was less than 1 mph.
I'd encourage you to monitor your speed more closely :cowboy:

Dictators. Best unintentional pun :rofl: