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jrm223

General Grabber AT2 upgrade

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So, my van is at a tire shop right now getting an upgrade to General Grabber AT2 all-terrains. Stock tires have 70K on them and are pretty well worn-down, one pair is at the wear bars and the other pair has a little bit left before the wear bars. I ordered 215/65R16 so I can gain 1/2" extra ground clearance because I scrape too often - but, of course, WalMart wouldn't put them on since they aren't stock-size. I ordered online since they weren't in-stock at my local store. Their worker told me "The tires are 6.67% bigger (I know that, I want more ground clearance) and your van is spec'd for extra-load capacity tires and the tires you bought are standard-load." I looked up the tire specs and Ford's axle specs (GAWR) - my van has 2716lb GAWR for each axle and the tires are rated 1653/ea thus 3306/pair?! 590lbs more capacity then the axle is rated for, but they're not high enough load capacity, that's hilarious!

 

Anywho, pics later after I get the van back. I'll have to schedule a service visit with Ford to reprogram computer for the new tire size and I also still need to get the door latch recall done. Hopefully these tires will help me not get stuck in my own yard like the stock ones did in spring of 2016... Had to get pulled out of my own yard, lol.

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Are you reprogramming the tires for speedo calibration?

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It'll be 70K before you'll know if the Generals were an 'upgrade' or not . . . . won't it?

 

Hopefully they can reprogram the transmission shift points  -  That would be a bigger issue to me than the speedo

 

Don

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I went from 215/55/16 size tire to 215/60/16 size tires.  The Ride improved  The speedometer error was marginal and the Transmission Shift quality and performance are unchanged. 

jrm233 I want a full up date on the driving impressions . Please keep track of the possible Scrub issues.  I am very happy with the changes I made  to My TC

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Well, one of my clients called as I was walking to the shop to pick up my van, so I didn't get any pics before the sun was down. After a couple miles around town, I barely hear more noise over the Continentals that came off, but I've had trucks with actual mud tires so naturally these AT's are a lot quieter than those. Highest speed around town is also 45MPH, so there might be a bit more noise once I'm going faster on the way home (70MPH between towns).

 

MRTN, I'm planning on bringing it to Ford to get reprogrammed (hopefully, but we all  know how tech's and SM's can be about these things) and I still need to get that door latch recall taken care of, so I'll need to schedule it to make sure they have the new latch first.

 

Beta Don, if these tires don't get stuck in my own yard, they'll be an instant improvement, lol. Although that only happened once. That said, they should also have less tendency to spin even on drive pavement, one issue that the Conti's had since new since they're such a hard compound. As for the trans shift points, I would think there wouldn't be a need to change them as long as the vehicle knows the actual road speed via correcting the tire size in the computer, but maybe I'm thinking about that wrong, idk. On trucks in the past, I put 33's on one that had like 29's stock and I shifted the manual (1989 F150 4.9L 4-speed granny) at the same RPM's as always. Also had swapped the stock 265/75R16's to 315/75R16's (31.6" to 34.6", 9.5% difference) on my 2003 F350 and didn't make any adjustments to the computer or auto trans there. The tire increase on my TC2 is only 6.7% increase, in comparison.

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I really didn't notice any increase in road noise up to 75MPH on the way home and I don't have any rear interior, either - no foam/vinyl floor, no plastic panels, etc. So mine is already a bit noisier than most cargo vans here, but not loud by any means. I did get one pic before leaving work with a parking lot light plus camera flash for some brightness.

 

WP_20171221_001.jpg

Edit: Oh yea, I also noticed they don't break traction as much on pavement or gravel. Same situations that had the traction control going crazy before, even when the Conti's were younger & meatier than now.

Edited by jrm223

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Thank you for the up date.

I think  the  Transmission control computer adapts the shift patterns automatically.  The only priority is the speedometer error is important. 

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10 hours ago, jrm223 said:

I really didn't notice any increase in road noise up to 75MPH on the way home and I don't have any rear interior, either - no foam/vinyl floor, no plastic panels, etc. So mine is already a bit noisier than most cargo vans here, but not loud by any means. I did get one pic before leaving work with a parking lot light plus camera flash for some brightness.

 

WP_20171221_001.jpg

Edit: Oh yea, I also noticed they don't break traction as much on pavement or gravel. Same situations that had the traction control going crazy before, even when the Conti's were younger & meatier than now.

 

Your new tires look great! I am curious tho.....in your first post you stated Walmart "would not" mount these tires. So, who installed the tires? At first glance you are correct that the weight rating on the new tires are over. LT tires when used on a SUV, light pickup or van use the full tire weight rating. P tires on the other hand used in the same application (load carrying vehicles, not pass cars) can only use 90% of the rating. The other issue is tire pressure. My van placard states rear tires to be inflated to 48#, while the Grabber AT2 215/65R16 states a max of 45# (info from tirerack) and the OEM Continental's are 51# max. The legalities are too overwhelming! 

 

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I had to bring them to another shop in town to get mounted since Walmart wouldn't do it because of corporate liability policies with the oversize and "underweight" aspects. It's been awhile since I looked, but I think my van shows 42F and 45R PSI on the sticker; I'll have to check that again in a bit. I always inflate all four to around 42-43PSI since I don't generally carry anywhere near full-load capacity. So far the tire pressure light has not popped up, so they must have put enough air in to make the computer happy, anyway.

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The Tire psi max is to insure that the tire will perform at the rated  load .  The placard  it there to make sure the supplied tires are not run with too little pressure for the load.  The new tires carry the same psi to rated load .  The tire will carry the load  at the indicated psi.

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Okay, I remembered wrong for my tire sticker - it's 44F & 48R, but I do roughly 44 all-around. I don't have a gauge with me to check the current pressure, though. The second pic is the back-edge of the driver side, closest to the door; I can get my fingers through the gap. Second pic is front-edge of passenger side by the bumper, a little more room up there.

WP_20171222_001.jpg

WP_20171222_002.jpg

WP_20171222_003.jpg

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WalMart has been a real stickler to exactly follow what's on the door jamb sticker for at least the last 20  years.  I've got a Miata which came with 185/60R14 tires and back in the day, running high performance Bridgestone RE-71's (developed as an OEM tire for Porsche) in 195/55R14 tires was the 'performance upgrade' for those who occasionally auto-crossed their cars  -  A really 'sticky' tire.   Because Bridgestone made that tire in that size specifically as the OEM tire for one of the little Japanese sport sedans, it was a really popular upgrade for Miata enthusiasts.  Same load rating, same overall circumference, but WalMart would not mount them . . . . unless I brought them just the wheels and not the car!

 

The next years Miata came out with super lightweight 15 inch wheels and 195/50R15's which are the same load rating and the same overall circumference as the 185/60R14's that came on my car.  Since performance rubber in ANY 14" size was getting scarcer than hen's teeth, I 'upgraded' to the 15" wheels and the 195/50R15's, again hauling just the wheels and my new tires over to WalMart to get them mounted and balanced

 

So long as I brought them only the wheels/tires and not the car, they were happy to mount them for me.  *IF* there was ever an accident causing death which might in any way be attributed to the improper size or load ratings of the tires, the first company named in the ensuing lawsuit would be the one with the deepest pockets, namely WalMart, so they just won't do it  -  Probably as a direct result of a lawsuit in the past

 

For your General Grabber AT2's, th load rating (98) is actually *greater* than the OEM Continentals (97) you took off  -  The only 'legal' stickler is the speed rating.  The Continentals were rated H, which is 130 mph, while the Generals are rated T which is 118 mph

 

Don

Edited by Beta Don

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Yeah, WalMart is a PITA when it comes to tires. They did not want to mount winter tires on my old RX7 without mounting them on all four tires. I brought them the tires and wheels by themselves and they mounted them. 

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3 minutes ago, Boomerweps said:

Yeah, WalMart is a PITA when it comes to tires. They did not want to mount winter tires on my old RX7 without mounting them on all four tires. I brought them the tires and wheels by themselves and they mounted them. 

 

With a rear-wheel drive like that, I can understand them wanting to do all four. What good is it being able to get moving if you can't steer well? lol, now a front-wheel drive it'd be less of a concern to have all four snow tires. Back tires would help stop, but not much help to move or steer.

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Any rubbing issues? I live in Colorado and can use all the extra clearance and traction I can get my hands on! Would love to do this upgrade

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Bump. I'm curious as I'm thinking of getting 215/65/16 also but all-season tires instead. I'm leaning towards the Hankook tires or maybe Goodyear.

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On 2/11/2018 at 8:22 PM, LukeConnect said:

Any rubbing issues? I live in Colorado and can use all the extra clearance and traction I can get my hands on! Would love to do this upgrade

 

 Nope,  I haven't noticed any rubbing issues and they've had probably a couple thousand miles, I forgot the mileage when I had them put on... I did get around to calculating the odometer difference more accurately, going from my project house to the one I live in is 83.9 miles and the odometer read 79.2 miles, giving a ratio of 1.059 instead of 6.7% (1.067) like the online tire calculators claimed. I still need to get it into Ford to hopefully have them reprogram the tire size and also still need the door latch recall done. MPG's have been 20.5-23.6 (corrected for actual miles traveled) the couple times I've checked it and I'll be checking the next tank-full again. I was averaging around 24MPG with the original tires. Texas speed limits - and likely my short 11.5 mile work commute - have killed my MPG's compared to when I lived in IL (26-28 MPG average up there with the lower speed limits and 50 mile former work commute).

Edited by jrm223
Grammar correction

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215/65R16 works out to be 27" diameter. That may qualify you as putting the tallest tire on without a lift. Maybe even champion.:thumbsup:

 

That's a really tight fit on the front. I don't if you ever get the van in a bind with the wheels turned full on but it might rub then. But maybe not. I have a pickup that is really close like that and that is the only situation when there is any rubbing. Even then its not terrible so I don't worry about it much. 

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On ‎12‎/‎21‎/‎2017 at 7:08 PM, G B L said:

I went from 215/55/16 size tire to 215/60/16 size tires.  The Ride improved  The speedometer error was marginal and the Transmission Shift quality and performance are unchanged. 

jrm233 I want a full up date on the driving impressions . Please keep track of the possible Scrub issues.  I am very happy with the changes I made  to My TC

 

I am doing a fit test so to speak on 225/60R16s on the front. It fits of course but I have not had the chance to drive it around to check for any scrubbing which it shouldn't. This is with a wheel with +40 to +42 offset so its bumped off just slightly from stock (had these just lying around). I bumped it out an additional 1.25" with a spacer just see how that affected the turning radius and boy is it tight.....but it still clears although I would be extremely surprised if there wasn't some rubbing issues with that particular setup (about +10ish and a little increased width). I took the spacers off because it was just a test to see where things might land if an adapter was used. 5x108 in a 16" wheel really is the bastard red-headed stepchild of the wheel world.

Moral to the story is that 225/60R16 will work although there will be an increased speedo error from your 215/60R16 setup. I have been wondering what is the point where gearing becomes an issue? I think jrm233 is at the limit in diameter and still be able to turn the wheel (without additional mods). 

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6 hours ago, OLDSCHOOLFOOL said:

Moral to the story is that 225/60R16 will work although there will be an increased speedo error from your 215/60R16 setup. I have been wondering what is the point where gearing becomes an issue?

The computer shifts the trans based on several inputs, one of which is the overall circumference of the tires.  I think the speedo error is of little consequence when compared to the error given to the computer generated shift points.  I'm sure you'll be able to drive it with whatever size tire you can cram in there, but performance and mileage will certainly be affected

 

Don

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Haven't been at work the last couple days because of ice & freezing rain here in Texas. I filled up my tank on Tuesday night and got 22.37 MPG (corrected for tire size). With the old tires, I was averaging around 24 MPG, so it's a 6.8% reduction if I'm doing my math right... But the previous tank was 23.6 MPG, which is a 1.7% reduction from the old tires.

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3 hours ago, Beta Don said:

The computer shifts the trans based on several inputs, one of which is the overall circumference of the tires.  I think the speedo error is of little consequence when compared to the error given to the computer generated shift points.  I'm sure you'll be able to drive it with whatever size tire you can cram in there, but performance and mileage will certainly be affected

 

Don

Certainly, it couldn't help but affect it, just a matter of to what degree. It's much harder to physically sense or "feel" the difference in an automatic than a stick shift. And it is more curiosity than concern.

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I have two sets of wheels and the Summer tires are 215/60/16, and the the current set of winters are stock 215/55/16 .  The size difference in my case is unnoticeable.  The Ride quality is the major asset in the size change. 

The vehicle mileage undergoes  a definite penalty  as the temperature  declines.  This must also be figured into the mileage equation along with  the tire size.     

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