GR Yaris Questions about my upcoming tuning/modification

Onehp said:
This is incorrect. The change is 1,2% but the OE speedo reads maybe 2-3% too high so you have some margin to reduce that overread. So it will be OK if they really check speedo vs GPS speed. But not if they assume speedo on OEM tyres is 100% correct (it is not)...
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This. And it also depends on the depth of tread from new. OD varies manufacturer to manufacturer, model to model. I went from 225/40 18 Yoko AD08R on an 8" rim. These were just under 4% out on the speedometer; 100 kph on the speedo was 96 and a bit actual. Fitted Yoko V107 235/40 18 to the same rims and these were now about 2% low (100 on the instruments is 98 actual).
 
for road use I'd stick to 225 width. any wider doesn't improve anything on road, just more noise, more fuel consumption, worse acceleration and performance in general.
 
Greetings everyone,
thanks again for the comments!


@Onehp & @Humptydumptyhadabigone

Thanks you two, I thought the exact same.
Sadly I also find very conflicting answers to this "problem“ online.
Some wrote that the TÜV demanded an adjustment of the speedometer and some said they did not demand it.

Some websites also write that up to -1,5% the TÜV won’t say no or lay you any stones in your path (which would be the case with my -1,2%).
In the end it seems like that this problem is no problem at all! :)


@Michael Knight

I will go with 235 width tyres.
I know that they generate more noise & have worse fuel consumption but these are no crucial points to me & I sometimes do track.

Performance wise I dont think that they are worse than 225/40 since when I read about 225/40 vs 235/40 last weekend the 235 width one almost always wins in test-categories like grip & handling in turns, driving over sloppy areas, not that subsceptible to pottholes, more traction & stability. (What I want in the summer)

225/40 on the other hand often wins in test-categories like noise, fuel economy, lightweightness and low resistance. (Which I would want for the winter)

Also, Toyota uses 235/40 tyres for their GRMN Yaris on 18x8 wheels I try to mimick. They probably use 235/40 tyres for a reason.

If 225/40 would be better I am 100% sure they would’ve went for 225/40 again like on the normal GR Yaris.
 
Welcome. You will not regret your choice ! My GR is now 2 years old not missed a beat at 45 k km and apart from the OEM camber bolts and 3 degrees is pretty much standard. I run Dunlop Direzza 3 tires all the time and am happy with them inspite of the extra noise ! A quick trip round Aus of 20 k last year showed what a great grand tourer this gem is . My advice is make haste slowly with modifying anything as the package is so good . The various GR sites are full of advice and wonderful ( presumably well healed ) Punters who have tried and tested practically everything up to 700 odd bhp ! Most
Parts have been changed for better or worse by quite knowledgeable people so worth an extended read. The old site is still worth a look for that reason although tis site is the bees knees ! I put LEB bulbs into Prius fog lights for improved side lighting and a bar for my trip , we rarely drive at night here because of jumping marsupials! Front wheel arch spats stop stones and some have put fancy mud flaps for little mud! The car has prodigious mid range poke and is above most normal punters range of super driving expertise! I love mine !
 
Greetings everyone,

I would like to thank you all for your help once again.

The BORBET DB8GT2 wheels are incoming very soon, the other parts will follow!

I would like to put some titan wheel nuts on my new wheels to save some unbalanced weight but I don't know if the OEM wheel studs (example picture attached since I don't know if I translated the 100% correct name for the part) contains any zinc or not.

Zinc and Titan react with each other and can lead to prematurely fail of the titan wheel nuts.

Stehbolzen_M12_1_3178_0.jpg


Help is very much appreciated!

Thanks in advance!
 
Wubziz said:
Greetings everyone,

I would like to thank you all for your help once again.

The BORBET DB8GT2 wheels are incoming very soon, the other parts will follow!

I would like to put some titan wheel nuts on my new wheels to save some unbalanced weight but I don't know if the OEM wheel studs (example picture attached since I don't know if I translated the 100% correct name for the part) contains any zinc or not.

Zinc and Titan react with each other and can lead to prematurely fail of the titan wheel nuts.

View attachment 18303

Help is very much appreciated!

Thanks in advance!
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I have used titan nuts for 0.5yr also thru winter and they look all clean to me. Not so of studs which seem to corrode as other components under the car, maybe need to replace in few years.
 
@Michael Knight I am very sorry to bother you once more, but since you seem to be experienced with titan nuts / titan products I would like to ask you some questions regarding these.

I thought about using titanium wheel studs (replacing the oem ones, example picture is in comment #26) & titanium lug nuts but when I search for this particular combination in the internet buzzwords like "seizing", "anti seize", "use manual wrench" or "fasten the titanium lug nuts with less torque then you would the steel ones" appear.

One side says it is awesome if you are on a quest trying to lose unbalanced weight and the other side says you should only use titanium wheel studs with aluminium lug nuts or titanium lug nuts with the oem wheel studs toyota builds into the car due to titanium + titanium ontop of each other without anti seize destroys the lug nuts and you cannot remove them anymore. (horror scenario)

What is the truth here?
Would I run into problems using titanium wheel studs & titanium lug nuts together?
 
Wubziz said:
@Michael Knight I am very sorry to bother you once more, but since you seem to be experienced with titan nuts / titan products I would like to ask you some questions regarding these.

I thought about using titanium wheel studs (replacing the oem ones, example picture is in comment #26) & titanium lug nuts but when I search for this particular combination in the internet buzzwords like "seizing", "anti seize", "use manual wrench" or "fasten the titanium lug nuts with less torque then you would the steel ones" appear.

One side says it is awesome if you are on a quest trying to lose unbalanced weight and the other side says you should only use titanium wheel studs with aluminium lug nuts or titanium lug nuts with the oem wheel studs toyota builds into the car due to titanium + titanium ontop of each other without anti seize destroys the lug nuts and you cannot remove them anymore. (horror scenario)

What is the truth here?
Would I run into problems using titanium wheel studs & titanium lug nuts together?
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not an expert with materials but would assume ti - pair should work well.
I swap tires every other month so seizing is not much of a concern. But maybe best to consult a more experienced car mech, just speaking out of own experience with ti nuts.
 
Michael Knight said:
not an expert with materials but would assume ti - pair should work well.
I swap tires every other month so seizing is not much of a concern. But maybe best to consult a more experienced car mech, just speaking out of own experience with ti nuts.
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Thanks for your information on that.

Sadly I dont know a car mech/person that has experience with Ti-products.

Maybe someone here on the forum has the experience?

Maybe opening a second thread with this particular question will lure in someone with enough knowledge on that topic.
 
Michael Knight said:
not an expert with materials but would assume ti - pair should work well.
I swap tires every other month so seizing is not much of a concern. But maybe best to consult a more experienced car mech, just speaking out of own experience with ti nuts.
Click to expand...
I agree with this, and I also have ti-nuts on another car with with steel studs. The seller told me to use nickel antiseize and absolutely nothing else. No problems at all after 2 seasons.
 
Apparently copper antisieze on Stainlees steel produces a reaction that can lead to cracking . Inter crystalline reaction !
 
Lanman said:
Apparently copper antisieze on Stainlees steel produces a reaction that can lead to cracking . Inter crystalline reaction !
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Maybe SCC or stress corrosion cracking. Bad juju but usually due to chlorine ions. Need to check mine though I have nickel based that I use mostly, the copper version was recommended to me for my titanium mountain bike. Definitely need to check.

Edit: avoid above 288C. Lead and zinc have similar reactions but temp is 427C.
Edit2: so using koprcote on my titanium fatbike is not good. At any temperature. Particularly as it is ridden on the beach. I strip it completely every year and haven't noticed any reaction.

Thanks for the heads up.
 
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