I hope this is a silly question -- based on my old analog, mechanical age, I suppose. I have an LR4 and the new Defender coming and am thinking of wheel size changes on one oe both... Question is: what happens to the speedometer accuracy and transmission shift points when the outer diameter tire size is changed on these two vehicles?

Are there others points of concern to consider?

Thanks !!

 

With the LR4 I used the Gap Diagnostic IIDTool to adjust for larger diameter tires. This tool is not yet available for Defender. I believe the biggest issue after fit, would be speedometer calibration

 

Hi

Thanks for starting the new thread for this question.

Lets look at this a little different. With the LR4, I started with a 29" tire that was stock and went to a 32" tire. That change represented a little over 10%. That is a pretty big jump, but not crazy like people do on full size trucks and some jeep upgrades.

With the Defender, going from a 32" tires to a 33" tire change is less drastic. It is only about a 3% change.


To put this in perspective, if you were driving down the interstate at an indicated 100mph on the speedometer, the change of 3% makes the car go 103 and the 10% you are traveling 110. One is pretty acceptable , the other you would for sure notice.

Same with power, 3% vs 10% is a big hit to take. Its still fine, but once again, you will likely notice one but not the other.


Does that help any?

Rob

 

Yes, this helps. Thanks to both of you ! Very good to learn from others.

 

When you took the LR4 to 32" did you lift it with Johnson roads (or some equivalent)? How did lifting it change the ride of the vehicle on and off-road and when towing?

Thanks!

 

Hi,

You have to lift or be content with rubbing most of the time.

The ride got firmer, but not harsh. This was due to stiffer sidewalls on the tires as well as the additional air in the air suspension. The ride wasn't nearly as noticeable as the performance change. I only touched briefly on what it does to the overall speed effect, but here is something I didn't point out earlier: larger tires generally are heavier too. That had a hit on performance too. Stock tires were around 38 pounds each, but going to a 32" tire took the weight up to 55 pounds each. Add larger wheels from the aftermarket, and the each corner went up 20 pounds. That doesn't help the already 10% loss in power.

My LR4 was one of the early ones that had the Jag 5.0 V8, so it never really bothered me that much. And to be honest, I never did tow anything with it.

The Defender will suffer quite a bit less if we can find a good compromise on tires. Room is limited and selections on 20" wheels is a bit more scarce.

In the end, you have to realize everything you do in life is a compromise. Changing anything will have different effects, but I always looked at it knowing what things I was willing to give up and what benefits I was looking to get.

Rob

 

Very helpful and interesting ! Thanks for sharing.

 

I used Johnson Rods and towed quite a bit. As mentioned above the larger diameter heavier tire did have an impact. My gas mileage dropped to about 13MPG average without a trailer and about 10MPG with. We also had the 5.0 so we still had plenty of power. The ride did seem a little more stiff (not significantly, I thought it was acceptable). I have been debating on the Defender the use of Johnson Rods vs Proud Rhino and think I've settled on the Johnson Rods even though it's less of a lift (1.5" vs 2"). I think this will be enough of a lift and have less impact to ride and performance. Considering other post on this forum I may go with a 265/60R20 this tire seems to work well for others and it's only a 1/2 inch increase in wheel diameter. I was debating the Lucky8 18" wheel solution but it seems too new and unproven, and I hate to be the guinea pig.

I hope some of that is helpful

 

I think those wanting a true off-road worthy Defender are going to want the 18" wheels and have better options for tires. They will likely be the ones getting the Proud Rhino lift as well. @" may be a bit more than I want to raise the Defender. I like the idea of 1" for a lift, but nobody does that. Based on having the Johnson Rods before, I will likely go with that lift for my solution.

I'm excited to see what other items Lucky8 comes up with. I have plenty of money to throw in many directions, and I believe that the Defender is going to be a great platform for many suppliers.

My plan is to go with a tire that is near 32.6-32.7" tall and maybe a bit wider. I also want a nice aggressive tire, so I have lots of work to get the right supplies in place.

Rob