Tire size question affect on AWD system

[SWUtah]

Stock size 275/60/18 (31 inch tire) Replacement tire 285/60/18 (31.5 inch tire) It is 1.5% bigger then stock. Question is if I replace my stock size with the 285/60/18's but keep my spare that is like new and is 1/2 inch smaller and 1.5% smaller, will it hurt my AWD system if I have a flat use the smaller spare for say 100 miles or until I can get the 285/60/18 fixed? I guess I am wondering how much wear takes place when the system has to compensate for a 1.5% difference in tire size on the same axle? Anyone else ever done this? The other a little more expensive solution is to just buy 5 new tires.

 

[spressomon]

Stock size 275/60/18 (31 inch tire) Replacement tire 285/60/18 (31.5 inch tire) It is 1.5% bigger then stock. Question is if I replace my stock size with the 285/60/18's but keep my spare that is like new and is 1/2 inch smaller and 1.5% smaller, will it hurt my AWD system if I have a flat use the smaller spare for say 100 miles or until I can get the 285/60/18 fixed? I guess I am wondering how much wear takes place when the system has to compensate for a 1.5% difference in tire size on the same axle? Anyone else ever done this? The other a little more expensive solution is to just buy 5 new tires.

The LC is a full time 4-wheel drive not AWD system. I think it is best to have the same size for all running tires. Having said that a spare is almost always going to be a different circumference than the running tires due to wear differences (how many people rotate their spares with their running tires?); I would think the manufacturer, Toyota in this case, has engineered this into their system. And the front and rear differentials provide the solution...as long as the CDL, front locker (if any) and rear locker are not engaged on hard/firm surfaces. This is my opinion...however I am not an 'expert".

 

[Jim_Chow]

What tires are those (285/60R18's)? I seem to only be able to find 275/65R18's (32") to replace the OEM size (Bridgestone revo's, yokohama geolander AT/S [BTW, the only LT 18" 275/65R18 other than BFG I've found]). Normally, I'd think the right side tires would turn more rev's per mile due to the slight slope of the road for drainage.

 

[hoser]

I wouldn't worry about the .5" diameter difference in tires when used for emergencies. If you are concerned, just drive a bit slower to keep the diff fluids cooler.

 

[flyfish4life]

What tires are those (285/60R18's)? I seem to only be able to find 275/65R18's (32") to replace the OEM size (Bridgestone revo's, yokohama geolander AT/S [BTW, the only LT 18" 275/65R18 other than BFG I've found]). Normally, I'd think the right side tires would turn more rev's per mile due to the slight slope of the road for drainage.

JIm - I think Nitto offers their Terra Grappler in 285/60/18. When I get ready to replace, it's between that and the 275/65/18 Revo, barring any new entrants into the market.

 

[Steph23]

I've got the 275/65/18 Revos, but I never upgraded the spare (still brand new). That's over a 1" difference and I've always wondered if that would pose a problem. Hopefully, I don't go flat.


BTW, flyfish...the Revos look great on 18" rims

 

[SWUtah]

I've got the 275/65/18 Revos, but I never upgraded the spare (still brand new). That's over a 1" difference and I've always wondered if that would pose a problem. Hopefully, I don't go flat.


BTW, flyfish...the Revos look great on 18" rims

You have 18 rims like I do, so how long have you had the REVO's? Are they quiet? compared to the OEM tires? I'm looking for tires that can handle heavy snow, but hold a balance, wear great and are as quiet as my Michelin pilot LTX's. Are these the tires?

 

[Steph23]

I've had them for 10k miles. They are not quite as quiet as the OEMs, but still better than BFGs. I haven't had any balance problems...good in sand...no snow in SE Virginia, though. They seem to be wearing pretty good at 40lbs PSI so far. I'm hoping to get anywhere between 40k-50k on them.

 

[SWUtah]

I've had them for 10k miles. They are not quite as quiet as the OEMs, but still better than BFGs. I haven't had any balance problems...good in sand...no snow in SE Virginia, though. They seem to be wearing pretty good at 40lbs PSI so far. I'm hoping to get anywhere between 40k-50k on them.

Thanks, wish Michelin made AT's in our size. The Pilot LTX's are rated on tire rack as not being as good in the snow as regular LTX's per tire rack ratings. They are rated "good" but its hard to know what that means.

 

[Steph23]

I hear ya...It's hard to make a judgement based on someone else's opinion, although it's a useful guide...Nothing compares to real world experience. Good luck!

 

[Jim_Chow]

I've got the 275/65/18 Revos, but I never upgraded the spare (still brand new). That's over a 1" difference and I've always wondered if that would pose a problem. Hopefully, I don't go flat.


BTW, flyfish...the Revos look great on 18" rims

Pics please!

Do you notice any difference in acceleration (albeit the tire size increase is only 3%) or when climbing on a mild grade w/ 275/65R18's when the 5spd can normally just hold 5th gear w/ the 275/60R18's? Does it downshift more often?

How quiet are the revo's compared to the Bridgestone HT's? The tirerack ratings suggest the HT's are noisier, but one has to bear in mind a different category of customer who buys the HT's/LTX's vs AT tires. I think the expectations for a quiet ride are much higher with those who buy highway or p-rated SUV tires.

 

[Steph23]

Pics please!

Do you notice any difference in acceleration (albeit the tire size increase is only 3%) or when climbing on a mild grade w/ 275/65R18's when the 5spd can normally just hold 5th gear w/ the 275/60R18's? Does it downshift more often?

How quiet are the revo's compared to the Bridgestone HT's? The tirerack ratings suggest the HT's are noisier, but one has to bear in mind a different category of customer who buys the HT's/LTX's vs AT tires. I think the expectations for a quiet ride are much higher with those who buy highway or p-rated SUV tires.

I would have to say that I noticed a very slight loss of acceleration, but there is still plenty of power coming from this engine; however this may partly be due my PSI of 40 lbs, which give it somewhat of a rougher ride, but much less rolling resistance. I haven't noticed any change in the feel of the 5 speed either. It still shifts very smoothly, but my mileage DID drop about 1mpg (which may be from the size increase).

The OEM Bridgestones HTs were a little less noisy, but these Revos are still quiet enough for me to hear the occasional rattle from anything that I put on the console near my shivering 4WD lever (during acceleration). Overall, I'm VERY pleased with them (looks, performance, & ride). I guess I should just cut & paste this review onto Tire Rack, huh?

 

[Greg B]

Stock size 275/60/18 (31 inch tire) Replacement tire 285/60/18 (31.5 inch tire) It is 1.5% bigger then stock. Question is if I replace my stock size with the 285/60/18's but keep my spare that is like new and is 1/2 inch smaller and 1.5% smaller, will it hurt my AWD system if I have a flat use the smaller spare for say 100 miles or until I can get the 285/60/18 fixed? I guess I am wondering how much wear takes place when the system has to compensate for a 1.5% difference in tire size on the same axle? Anyone else ever done this? The other a little more expensive solution is to just buy 5 new tires.

Go ahead and replace the tires but not the spare, then throw the spare on once you get home and drive it around and see if it causes you any problems. When I went to 295's on my main tires and a 255x85 on my spare I was worried about the same thing. In this case, what people say can make you feel OK, but for true peace of mind, test it yourself.

 

[EdsCruisin]

You can compensate by overinflating the spare and/or dropping pressure in the others. This will adjust the diameter primarily, but not the circumference much, so the tires may exhibit different "gain" while rolling.

I figure that a spare is a spare and unless I can find a spare of the same size, I will only use it temporarily, until I can get the other tire fixed.

Another solution I have used before was to ask the tire shop for a used spare that matches your other four. Tire shops typically collect the tires they remove for recycling. They charge a recycling fee, so they don't mind if you want to reuse a tire. They profit by mounting it again. Once again, it is a spare, so it doesn't need 60K worth of tread.

 

[Morbo]

Steph23

I like the looks of your rig. What year and color name?

 

[firetruck41]

IIRC, the 100 has an open center diff, not a viscous coupler like the FZJ80, so it shouldn't matter, in that regard. The only concern I would have is whether vsc/traction control would be constantly activated. I dunno...

 

[Steph23]

Thanks, Morbo...It's an '03 and the color is called Black Garnet Pearl.

 

[SWUtah]

I would have to say that I noticed a very slight loss of acceleration, but there is still plenty of power coming from this engine; however this may partly be due my PSI of 40 lbs, which give it somewhat of a rougher ride, but much less rolling resistance. I haven't noticed any change in the feel of the 5 speed either. It still shifts very smoothly, but my mileage DID drop about 1mpg (which may be from the size increase).

The OEM Bridgestones HTs were a little less noisy, but these Revos are still quiet enough for me to hear the occasional rattle from anything that I put on the console near my shivering 4WD lever (during acceleration). Overall, I'm VERY pleased with them (looks, performance, & ride). I guess I should just cut & paste this review onto Tire Rack, huh?

That's a real nice balanced size for the 18" wheel. Does anyone think a dealer would give you any warranty issues because you went from 275/60/18 tires to 275/65/18 tires? I know it would extend the mileage part of your warranty just a little

 

[Jim_Chow]

That's a real nice balanced size for the 18" wheel. Does anyone think a dealer would give you any warranty issues because you went from 275/60/18 tires to 275/65/18 tires? I know it would extend the mileage part of your warranty just a little

I've considered that, since you are in a roundabout way altering the mileage on the odometer. Technically, the warranty could be voided.

Since the speedo also thinks you're going slower than you are, I would guess the tranny would shift slightly later than normal, so maybe that's part of your 1mpg loss. On paper, both the 275/60R18 Bridgestone HT and 275/65R18 revo weigh 40 lbs each. The other part of the loss is the small 1/2" greater diameter. I'm leaning towards going w/ the Yokohama AT/S in the OEM size (to be released in early '07) when the time comes to play it safe on the warranty.

Is there any way to recalibrate the speedo to account for the 3% tire size increase?

 

[NMuzj100]

Is there any way to recalibrate the speedo to account for the 3% tire size increase?

Some have used a Superlift Truspeed unit, Slee OffRoad was selling them but they aren't on their website anymore. Has two settings so you could switch between two sets of tires. (~$200)
http://www.superlift.com/products/misc/truspeed.asp
Slee OffRoad install in an 80

You could also try a "YellR" converter. About $100.
www.yellr.com
MUD review and 80 install

I was looking at this Dakota Digital Speedometer Signal Interface Unit but it would be riskier since I would be the first. It also has an ABS system warning and it is hard to tell if it is a serious warning or generic lawyer print. (~$80)

I wouldn't add a calibration unit just to get the speedo to indicate a true speed but if it improved the shift points then it would be worthwhile to me.