Question For Alignment Experts:

[swathdiver]

Was looking up the alignment specs for my truck and noticed that there are different caster settings for each brand of tire. Why would that be?

 

[grim hurst]

Was looking up the alignment specs for my truck and noticed that there are different caster settings for each brand of tire. Why would that be?

For every new tire you buy, for instance buying a different size or whatever. Youll need to get them properly balanced so you wont have premature tire wear and most tires have warranties for this.

Caster:
Refers to the angle of the steering axis, which is the suspension component supporting the wheel and tire assembly. You can visualize the caster as an imaginary line that bisects the tire’s upper and lower ball joints. The caster can be negative, centered, or neutral. A properly aligned caster contributes to steering feel and high-speed stability.

Camder:
Describes the tire’s inward or outward tilt, when viewed from the front. Negative camber refers to a tire tilted to the right, while positive camber refers to a tire tilted to the left. This adjustment can maximize the tire-to-road contact, and account for changes in force as a vehicle turns. Out of each alignment adjustment, camber has the widest range of recommended settings. This range can accommodate different vehicle handling characteristics. Higher negative camber suits those who corner aggressively, while less negative camber suits those who perform very little hard cornering.

Its like how sport car authusist like to have it lowered and making there tires outward tilt. I don’t know the benefits.

And size matter. Ive had 16” stocks and up graded to 20” i was told to get a alignment, ad soon i drove it id notice a change. My front wheels were inward like “pigeon toed”.

 

[kbuskill]

I think it has more to do with the RPO codes listed vs the tires listed.

But I didn't bother to look up those RPO codes to see the difference, just my guess.

 

[swathdiver]

The RPO codes relate to tire and wheel sizes and brand of tire.

 

[iamdub]

Not an alignment expert here, but I was a certified tire tech in my younger years. The actual size of a tire can vary considerably between brands and especially between tire types. One brand's 275/55-20 touring tire can be a couple millimeters wider or narrower or shorter or taller than another brand's touring tire. Then there's the same brand but different type, such as the Goodyear Eagle 275/55-20 that came stock on my 2WD LTZ having a slightly narrower section width than the Goodyear Wrangler 275/55-20 that came on the 4WDs. If the alignment specs are specific to the caster, I'd venture to guess that that would be for better on-center feel between the tire types. An all-terrain tire on a 4WD could need different caster settings than a street/touring tire on a 2WD. Also, the 4WD would be a little higher, putting the control arms at a different angle, requiring slightly different alignment settings. It's all probably minor differences, but geometry is geometry and the engineers specify certain numbers to be held.

But, what does the pic you attached have to do with any of this?

 

[swathdiver]

Not an alignment expert here, but I was a certified tire tech in my younger years. The actual size of a tire can vary considerably between brands and especially between tire types. One brand's 275/55-20 touring tire can be a couple millimeters wider or narrower or shorter or taller than another brand's touring tire. Then there's the same brand but different type, such as the Goodyear Eagle 275/55-20 that came stock on my 2WD LTZ having a slightly narrower section width than the Goodyear Wrangler 275/55-20 that came on the 4WDs. If the alignment specs are specific to the caster, I'd venture to guess that that would be for better on-center feel between the tire types. An all-terrain tire on a 4WD could need different caster settings than a street/touring tire on a 2WD. Also, the 4WD would be a little higher, putting the control arms at a different angle, requiring slightly different alignment settings. It's all probably minor differences, but geometry is geometry and the engineers specify certain numbers to be held.

But, what does the pic you attached have to do with any of this?

Great info Chris. The pic was the alignment spec sheet for 2009 Yukons, Tahoes, Suburbans and XLs with different drives and tire sizes and brands. I don't see it up there now.

 

[iamdub]

View attachment 196537


Great info Chris. The pic was the alignment spec sheet for 2009 Yukons, Tahoes, Suburbans and XLs with different drives and tire sizes and brands. I don't see it up there now.

The pic I saw looked to be a screenshot with a chart for diagnosing something (a misfire?). Had stuff along the lines of "check injectors" and "bad gas" with a few things circled in blue.

What's there now makes sense.

 

[swathdiver]

I did a cut and paste and the photos get swapped out after a while it seems when I do that. Will try not to be lazy and actually upload a photo from now on!