Wheel and Tire Upgrades

[skigolfmike]

I am thinking of upgrading from 17” stock alloy wheels to 18” wheels and tires on my 2015 Jetta TDi SEL. I’ve already upgraded the suspension with stiffer sway bars and the Komi Active shock/strut kit. I’m thinking the Verdestien Quadtrac Pro+ tire 225 40/18 and the pictured wheels.

IMG_0380.jpeg

• skigolfmike
• Dec 12, 2024

2015 Jetta TDi SEL

 

[hskrdu]

Not sure if there is a question in there, but since you posted....
Many of us would not term this an "upgrade." I ditched the 17's on the GSW for 16's! The 18" wheel/tire combination is usually heavier (which hurts fuel economy and increases weight at each corner- with the associated impacts to driving). The smaller sidewalls can make all but the smoothest roads feel rough, and some owners see an impact to their suspension (and spine). Those tires are often more susceptible to damage from road hazards- not to mention the higher cost usually associated with taller tires, many of which have lower service life. Just my .02.

 

[Nuje]

Why not go with 22" rims and 25-aspect tires?
(That was not serious - but just pointing out the folly of going further down that path of taller, heavier, more expensive rims and their accompanying tires.)
IOW, I'm just reiterating @hskrdu above.

 

[skigolfmike]

Yes, I am aware that it might make the quality of the ride a bit worse. I already made the ride a bit worse with the suspension upgrades, so what’s a little more. These wheels are the same weight as the stock 17” wheels, so weight isn’t really an issue. I admit, I’m thinking it looks good and, due to the tires, I think it will handle a little better. Maybe I’m just crazy.

 

[oilhammer]

I'd be looking for the Jetta Hybrid's 15" light weight alloy wheels, wrap them in the stock 195-65-15-91H tires and enjoy the nice smooth quiet ride, the better fuel economy, and the exceptionally longer tire life out of the less costly tires.

 

[Nuje]

I'd be the same.
And I'd wager that @oilhammer's and my age demographics are a lot closer to each other (and a larger number) than that of @skigolfmike.

 

[hskrdu]

Yes, I am aware that it might make the quality of the ride a bit worse. I already made the ride a bit worse with the suspension upgrades, so what’s a little more. These wheels are the same weight as the stock 17” wheels, so weight isn’t really an issue. I admit, I’m thinking it looks good and, due to the tires, I think it will handle a little better. Maybe I’m just crazy.

Not crazy, just with different goals than most members here. It sounds like you know what you'll be getting into, which is key. The weight of the wheels may be similar, but usually the tires will be heavier- and sometimes by a notable amount. The Verdestien you mentioned are close to 23lbs, if the internet is to be trusted. It's weight at the "worst" place, which impacts you at every take-off from a start.

Years ago, some of the Mk4 enthusiasts here spent time with poly bushings, modded suspension, and wider tires, but I'd say most eventually found the OE VW setup was actually quite good, if not superior to the "upgrades." Of course, the vortexers are still doing this- I see their cars all the time at the salvage yards: bagged, sagged, lowered, shaved, abandoned and left for junk.

And OH is spot on with the noise- my 17's were much louder on the Mk7 than the 16's, but some of that is tire choice.

As long as you are getting larger, heavier tires, maybe you can offset with lighter 18" GTI wheels. The Praetorias(?) are black and no too dissimilar from the ones pictured. Plus they are OE, which immediately elevates your cred.

 

[skigolfmike]

I’ll stick with the Sport Edition 15-2 18” in black. I have black caliper paint to paint the stock calipers. Probably a good thing since they will be more visible. Black is more subtle than red or yellow and I want to kind of keep this car as a sleeper. The GTi wheels are cool, but way more expensive than these.

I’ve got a Malone Stage 2 tune through Tunezilla, but I’d like more. ECS Tuning got rid of their stage 3 tune, which would have been about as far as I wanted to go. If I really want to go fast, I’ll by an R.

 

[privateTDIjet]

My 18" Detroit mags blew 3 tires in 4 months. One blew up on a bridge, costing me a 250$ tow, another one in the middle of nowhere and finally one blew out on it's own after having a bubble on the side of it for a week. Its a love hate relationship for me. I love cornering and the looks that come with these but they take their toll on my wallet. Not to mention the 225/40/18 tires are hard to find used around here.

 

[skigolfmike]

Interesting, the Sport Edition A15-2 18” wheels are lighter than the stock 17” wheels by 9 lbs. I was wondering what to do with the old wheels. I decided to keep them and I will put winter tires on them so I can go winter, summer in the future. I have not mounted on the car yet since they delivered after dark and it’s pretty cold out. Might try mounting tomorrow if it doesn’t snow.

IMG_1861.jpeg

• skigolfmike
• Dec 19, 2024

 

[Lug_Nut]

Pay attention to where that weight is located. The radial location of that weight absolutely affects rotational acceleration (and deceleration).
A larger diameter wheel has its rim further out from the rotation axis than a smaller one and requires more force to spin up (or slow down) even if the two rims are the same weight. If the rim is wider, that often necessitates a wider tire. Most of that tire weight/mass is in the increased tread and belt rubber and steel volume. A 'savings' of 8 lb in the wheel is a net performance loss if the tire needed is 8 lbs heavier.
A brake rotor that is 1 lb heavier is LESS detrimental than a tire that is 1 lb heavier.

While we're on rotational inertia: "Gaining power" by gaming the dyno with a pound lighter flywheel is totally negated by a larger diameter wheel and tire set that is just a few ounces heavier.
Bicycle racers with much low power to weight ratio had a saying that an ounce in the wheel was equal to a pound in the bike frame.

Now, if you're looking for bigger peacock feathers to attract a mate, go for it. I swapped from 16s to 17s on my B5.5 because I liked how they looked. Lost ride quality, lost fuel economy, but my perception of the aesthetics was improved enough.

 

[skigolfmike]

I got the wheels and tires yesterday and mounted them today. Got to compare to the OEM 17” wheels with the Pirelli tires to the Sport Edition 18” wheels and the Vredestein (sp?) Quadtrac Pro+ tires. I like the looks (see below), it really changed the looks of the car. I’m definitely going to have to paint the calipers now. I do have black Caliper paint for doing just that. As far as weight, these wheels and tire were lighter than stock. Not by a lot, it enough to be noticeable. Road noise and ride didn’t really suffer with this combo IMHO. I drove on surface streets and the HyWay. Handling is much sharper, but that could be due to the state of these tire vs. the Pirellis with a lot of wear. It was cold and the roads were damp, but traction was good. So far, so good

Jetta Sport Edition AR15-2 Wheels

• skigolfmike
• Dec 20, 2024

SE AR15-2

Here you can see a comparisons of the OEM wheels to the SE wheels.

Jetta old and new wheels

• skigolfmike
• Dec 20, 2024

Old and new

 

[northern diesel]

Pay attention to where that weight is located. The radial location of that weight absolutely affects rotational acceleration (and deceleration).
A larger diameter wheel has its rim further out from the rotation axis than a smaller one and requires more force to spin up (or slow down) even if the two rims are the same weight. If the rim is wider, that often necessitates a wider tire. Most of that tire weight/mass is in the increased tread and belt rubber and steel volume. A 'savings' of 8 lb in the wheel is a net performance loss if the tire needed is 8 lbs heavier.
A brake rotor that is 1 lb heavier is LESS detrimental than a tire that is 1 lb heavier.

I cringed while reading this- I am sure you are right and I am second guessing my most recent big purchase of a rim and tire combo that definitely is adding weight. I am waiting to install it still because I am doing a big brake upgrade and don’t see the point of putting on brand new parts to get thrashed by winter -
Once I got the BFG KO2s mounted on the 16” slightly wider rims - I noticed they were remarkably heavier than my stock ones.
My main cringe is that while I have a tune and the possibility to request more power - I worry about the wear and tear this heavier set up will cause.
Could this add to cam wear ?
Or is it mainly going to be felt in wheel bearings and brakes ?

 

[northern diesel]

Those look good ! No denying that aesthetics have a place in the hierarchy of car needs

 

[skigolfmike]

I cringed while reading this- I am sure you are right and I am second guessing my most recent big purchase of a rim and tire combo that definitely is adding weight. I am waiting to install it still because I am doing a big brake upgrade and don’t see the point of putting on brand new parts to get thrashed by winter -
Once I got the BFG KO2s mounted on the 16” slightly wider rims - I noticed they were remarkably heavier than my stock ones.
My main cringe is that while I have a tune and the possibility to request more power - I worry about the wear and tear this heavier set up will cause.
Could this add to cam wear ?
Or is it mainly going to be felt in wheel bearings and brakes ?

Rotating weight has a lot to do with where the weight is located on the wheel. Closer to the center, good. Farther away from the center bad. Theoretically, it is possible to have a lighter wheel and tire combo with the weight out by the rim have more "rotating weight" than a heavier wheel and tire combo with the weight concentrated by the hub. Has to do with angular momentum or something like that.

 

[skigolfmike]

One side effect of these 18” wheels is it makes my brake disks look small. Now I have to decide if I should get bigger disks. Ugh!

 

[Nuje]

Rotating weight has a lot to do with where the weight is located on the wheel. Closer to the center, good. Farther away from the center bad.

For those having trouble envisioning the how/why of this, imagine holding 5lb dumbbell in your hand. And how much effort it takes to rotate that around its long axis - just holding the handgrip area and rotating it side-to-side.

Then imagine that same 5lb weight, but as a 10ft. aluminum pole - how quickly / easily can you do the same thing: hold it in the middle and rotate it end-to-end (parallel to the ground)?

Same mass / weight. But how that mass is distributed matters a lot to how much force it takes to start or stop its movement.

 

[privateTDIjet]

One side effect of these 18” wheels is it makes my brake disks look small. Now I have to decide if I should get bigger disks. Ugh!

I think its a bit silly if you don't have the money for it. If you do, go ahead but spending a lot on a big brake kit for a jetta is not gonna turn heads.

 

[JordanTr]

Rotating weight has a lot to do with where the weight is located on the wheel. Closer to the center, good. Farther away from the center bad. Theoretically, it is possible to have a lighter wheel and tire combo with the weight out by the rim have more "rotating weight" than a heavier wheel and tire combo with the weight concentrated by the hub. Has to do with angular momentum or something like that.

There are 2 parameters at play here: True mass (lbs or kg) and momentum of inertia (mass*distance^2) which takes into consideration the mass distribution.

I actually build a little calculator in excel for comparing the weight and moment of inertia calculations for varying wheel setups for the Allroad project. I was hoping to validate for myself that I could upsize to forged 18” or 19” wheels without an excessive penalty on either mass or inertia. It also clearly shows that forged 16” wheels are the best selection from an unsprung weight and moment of inertia perspective. If you use the boat anchor 2 piece wheels that some Allroads came with, there are some gains to be had.
I’ll have to share some of the results and assumptions once I get back to a laptop.

I found that most tires of the same width and rolling diameter are similar weights regardless of rim diameter. For example: 235/50/18, 28#, 27.3” vs 235/55/17, 27#, 27.2” (Pirelli P7 data from TireRack). Obviously upsizing a rim and losing weight is a challenge so @oilhammer has good advise of running the smallest rims that will clear the brakes and you’ll typically minimize unsprung weight and inertia but there are no tail feather benefits!

 

[skigolfmike]

I think its a bit silly if you don't have the money for it. If you do, go ahead but spending a lot on a big brake kit for a jetta is not gonna turn heads.

Since I kept the 17” wheels to put winter tires on, I’m afraid I could go too big. The other issue is, it’s a lot of money and really I’d have to do the fronts and rears to keep the brake balance right. What I am considering doing is putting GLi brake disks on the front and painting the calipers with high temp black paint. Stock disks are 288mm and the GLis are 312mm. Plus, they are slotted and drilled.

BTW, the tires have a lot of grip. I had P7s before and they were good in the dry, but sucked in the wet. The Vredesteins are way better in the wet. Happy so far.

 

[scrambld]

Since I kept the 17” wheels to put winter tires on, I’m afraid I could go too big....What I am considering doing is putting GLi brake disks on the front and painting the calipers with high temp black paint. Stock disks are 288mm and the GLis are 312mm.

Different car, but my '15 Passat (MK5 underneath) had 312mm front disks and rear I forget... 288mm I recall. The rears looked small inside my oem 18's. I was underwhelmed with the oem brake performance feel....may have just been perception. I found clean used rear 2008 R32 calipers/brackets, used new SS brake hoses, new 310mm vented rotors,, and aftermarket dust shields (OEM too pricey). It looks OEM and I feel brake performance, feel, and looks are increased. Front was simple too 2008 R32/Passat VR6 4-MO: calipers/brackets/OEM dust shields, and new 345mm rotors. They do fit under my 17" OEM wheels for winter use. Everything painted gloss black to not draw attention. I know the service tech at my local VW dealer was impressed.
Did it add weight and all the aforementioned negatives? I'm sure. But it looks better, fills in the wheel cavity, and my perception is better brake feel, brake torque/leverage coming from larger rotors (slightly larger front caliper pistons) with no discernable increase in pedal travel vs say a 6pot 17/18Z brembo caliper up front. Of note, I do have Macan 4pot calipers/hoses to try up front, they bolt on. Hopefully small enough combined piston volumes to not be too noticeable.

 

[skigolfmike]

Different car, but my '15 Passat (MK5 underneath) had 312mm front disks and rear I forget... 288mm I recall. The rears looked small inside my oem 18's. I was underwhelmed with the oem brake performance feel....may have just been perception. I found clean used rear 2008 R32 calipers/brackets, used new SS brake hoses, new 310mm vented rotors,, and aftermarket dust shields (OEM too pricey). It looks OEM and I feel brake performance, feel, and looks are increased. Front was simple too 2008 R32/Passat VR6 4-MO: calipers/brackets/OEM dust shields, and new 345mm rotors. They do fit under my 17" OEM wheels for winter use. Everything painted gloss black to not draw attention. I know the service tech at my local VW dealer was impressed.
Did it add weight and all the aforementioned negatives? I'm sure. But it looks better, fills in the wheel cavity, and my perception is better brake feel, brake torque/leverage coming from larger rotors (slightly larger front caliper pistons) with no discernable increase in pedal travel vs say a 6pot 17/18Z brembo caliper up front. Of note, I do have Macan 4pot calipers/hoses to try up front, they bolt on. Hopefully small enough combined piston volumes to not be too noticeable.

I did think about 4 piston calipers with 345mm rotors up front. Good to know the 345s would fit with the 17” wheels. I’m not sure I want to spend that much money right now though.

 

[scrambld]

I was lucky to find bone yard front calipers/brackets off a 2008 Passat V6 4-MO (same calipers except Passat has a screw on/off vibration dampner ...shipped...I used Car-Part.com), bought new rotors/pads/hoses/dust shields obviously. The rear (had to be R32 for the mechanical E- brake vs Elect) I was lucky too, found rebuilt calipers/brackets off VWvortex....again new rotors/pads/hoses/aftermarket dust shields. Wasn't too bad.

 

[JordanTr]

As promised, I'll share some of the details from my spreadsheet on wheel and tire inertias. Most of these are tailored to B4 or C5 sized tires, but the principles don't change.

The model uses these assumptions: Rim inertia: 60% of the mass is at nominal diameter +/- 1", remaining 40% mass is a disc at 57mm to nom. diameter -1". For tires, I assumed OD-1.5" tread area holds 50% mass, beads at dia to dia +1" hold 20% of the mass, and the remaining 30% is in the sidewalls at dia +1 to OD - 1.5". Obviously this isn't perfect and it would vary between very short sidewalls and tall sidewalls, but for sizes somewhat close to each other, I think it gets into the ballpark.

A lot of the total inertia is in the bead of the tire so it's difficult to have a huge effect on inertia without changing overall rolling diameters or tire widths. See C5 examples 2/3/4 and B4 example 2.
At times, upsizing the rims can increase inertia but maintain the same weight. See B4 #4 and C5 #2/5.
Both B4 and C5 #1 drop the rim diameter but maintain tire sizes. This yields the best results.

B4 examples:
1. B4 OEM steelies to 14" forged Fuchs with 185/70/14 tires on both: 4 lbs lighter, 13% lighter, and 9% lower inertia.
2. B4 stock from 185/70/14 to 195/75/14: 4lbs/13% heavier, 27% more inertia, 5% taller
3. B4 stock/185/70/14 to 17x7.5" TT wheels 215/40/17: 50% more inertia, 11lb/35% heavier per corner. OUCH!
4. B4 stock/185/70/14 to 16" CLK320 wheels 195/50/16: 13% more inertia but same weight
5. B4 stock/185/70/14 to 15" A2 pepperpot 185/65/15: 10% more inertia, 1lb/3% lighter, 1% taller

C5 Allroad example:
1. OEM 2P 17x7.5" 225/55/17 to CLK320 215/65/16: 29% less inertia, 17.5lb/31% lighter, 1% taller. Wow!!
2. OEM 2P 17x7.5" 225/55/17 to R8 RR 19x11 275/35/19: 8% more inertia, same weight, 2% taller
3. OEM 2P 17x7.5" 235/55/17 to R8 FR 19x8.5 245/40/19: 6% less inertia, 11lb/19% lighter, 2% shorter
4. OEM 2P 17x7.5" 235/55/17 to R8 FR 19x8.5 245/45/19: 3% more inertia, 9lb/16% lighter, 2% taller
5. OEM 2P 17x7.5" 235/55/17 to S5 cast 19x9 255/40/19: 12% more inertia, same weight, 1% shorter
6. OEM 2P 17x7.5" 235/55/17 to Macan 18x9 245/50/18: 3% more inertia, 6lb/11% lighter, 1% taller

Obviously there are a few variable at play but this gives a general idea!